Expandable fusion device and method of installation thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes body, a first endplate, and a second endplate, a middle ramp piece, a stem, and two ramp pins. The middle ramped piece is operable to move to generate lordotic expansion of the first and second endplates followed by parallel expansion. The fusion device is operable to be deployed down an endoscopic tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. applicationSer. No. 15/189,188, filed on Jun. 22, 2016, which is acontinuation-in-part of U.S. Ser. No. 15/014,189, filed Feb. 3, 2016,which is a continuation-in-part of U.S. patent Ser. No. 14/109,429 filedon Dec. 17, 2013, which is a divisional application of U.S. patentapplication Ser. No. 12/875,818 filed on Sep. 3, 2010, now U.S. Pat. No.8,632,595, the entire disclosures of which are incorporated by referenceherein.

BACKGROUND

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY

In an exemplary embodiment, the present invention provides an expandablefusion device capable of being installed inside an intervertebral discspace to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. In one embodiment, thefusion device includes a central ramp, a first endplate, and a secondendplate. The central ramp may be capable of moving in a first directionto push the first and second endplates outwardly and into an unexpandedconfiguration. The expandable fusion device may be capable of beingplaced into the disc space down an endoscopic tube and then expandedinto an expanded configuration.

In an exemplary embodiment, an apparatus may be provided comprising: afirst endplate for an intervertebral implant, wherein the first endplatemay comprise a first plate portion having a first upper surface and afirst lower surface, wherein the first endplate further comprises firstfront ramped portions extending away from the first lower surface andfirst rear ramped portions extending away from first lower surface. Theapparatus may further comprise a second endplate for an intervertebralimplant, wherein the second endplate may comprise a second plate portionhaving a second upper surface and a second lower surface, wherein thesecond endplate further comprises second front ramped portions extendingaway from the second lower surface and second rear ramped portionsextending away from second lower surface. The apparatus may furthercomprise a body positioned between the first endplate and the secondendplate, wherein the body may comprise rear endplate engaging ramps.The apparatus may further comprise a driving ramp positioned at a frontend of the apparatus, wherein the driving ramp comprises front endplateengaging ramps. When the apparatus is in an unexpanded configuration,the rear endplate engaging ramps and the front endplate engaging rampsmay have ramp angles with respect to a longitudinal axis of theapparatus that differ from ramp angles of the first rear ramped portionsand first front ramped portions of the first endplate with respect tothe longitudinal axis. The apparatus may be configured such thatmovement of the driving ramp in one direction causes the first andsecond endplates to move apart and a movement of the driving ramp in asecond direction causes the first and second endplates to move towardsone another.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 2 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 3 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 4 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 5 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 6 is a side view of the expandable fusion device of FIG. 1 shown inan unexpanded position in accordance with one embodiment of the presentinvention;

FIG. 7 is a side view of the expandable fusion device of FIG. 1 shown inan expanded position in accordance with one embodiment of the presentinvention;

FIG. 8 is a perspective view of the central ramp of the expandablefusion device of FIG. 1 in accordance with one embodiment of the presentinvention;

FIG. 9 is a perspective view of the driving ramp of the expandablefusion device of FIG. 1 in accordance with one embodiment of the presentinvention;

FIG. 10 is a perspective of an endplate of the expandable fusion deviceof FIG. 1 in accordance with one embodiment of the present invention;

FIG. 11 a perspective view showing placement of the first endplate of anembodiment of an expandable fusion device down an endoscopic tube andinto the disc space in accordance with one embodiment of the presentinvention;

FIG. 12 is a perspective view showing placement of the second endplateof the expandable fusion device down an endoscopic tube and into thedisc space in accordance with one embodiment of the present invention;

FIG. 13 is a perspective view showing placement of the central ramp ofthe expandable fusion device down an endoscopic tube and into the discspace in accordance with one embodiment of the present invention;

FIG. 14 is a perspective view showing expansion of the expandable fusiondevice in accordance with one embodiment of the present invention;

FIG. 15 is a side schematic view of the expandable fusion device of FIG.1 having different endplates;

FIG. 16 is a partial side schematic view of the expandable fusion deviceof FIG. 1 showing different modes of endplate expansion;

FIG. 17 is a side schematic view of the expandable fusion device of FIG.1 with artificial endplates shown between adjacent vertebrae;

FIG. 18 is a front perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 19 is a front perspective view of the expandable fusion device ofFIG. 18 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 20 is a rear perspective view of the expandable fusion device ofFIG. 18 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 21 is a rear perspective view of the expandable fusion device ofFIG. 18 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 22 is a side view of the expandable fusion device of FIG. 18 shownin an unexpanded position in accordance with one embodiment of thepresent invention;

FIG. 23 is a side view of the expandable fusion device of FIG. 18 shownin an expanded position in accordance with one embodiment of the presentinvention;

FIG. 24 is a perspective of an endplate of the expandable fusion deviceof FIG. 18 in accordance with one embodiment of the present invention;

FIG. 25 is a perspective view of the central ramp of the expandablefusion device of FIG. 18 in accordance with one embodiment of thepresent invention;

FIG. 26 is a side view of the central ramp of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 27 is a top view of the central ramp of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 28 a perspective view showing placement of the central ramp of theexpandable fusion device of FIG. 18 in accordance with one embodiment ofthe present invention;

FIG. 29 is a perspective view showing placement of the first endplate ofthe expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 30 is a perspective view showing placement of the second endplateof the expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 31 is a perspective view showing placement of the actuation memberof the expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 32 is a perspective view showing expansion of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 33 is a front perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 34 is a front perspective view of the expandable fusion device ofFIG. 33 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 35 is a rear perspective view of the expandable fusion device ofFIG. 33 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 36 is a rear perspective view of the expandable fusion device ofFIG. 33 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 37 is a side cross-sectional view of the expandable fusion deviceof FIG. 33 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 38 is a side cross-sectional view of the expandable fusion deviceof FIG. 33 shown in an expanded position in accordance with oneembodiment of the present invention;

FIG. 39 is a perspective of an endplate of the expandable fusion deviceof FIG. 33 in accordance with one embodiment of the present invention;

FIG. 40 is a rear perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 41 is a rear perspective view of the expandable fusion device ofFIG. 40 shown in a partially expanded position in accordance with oneembodiment of the present invention;

FIG. 42 is a rear perspective view of the expandable fusion device ofFIG. 40 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 43 is a side exploded view of the expandable fusion device of FIG.40 in accordance with one embodiment of the present invention;

FIG. 44 is a side cross-sectional view of the expandable fusion deviceof FIG. 40 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 45 is a perspective view of an endplate of the expandable fusiondevice of FIG. 40 in accordance with one embodiment of the presentinvention;

FIG. 46 is a perspective view of the central ramp of the expandablefusion device of FIG. 40 in accordance with one embodiment of thepresent invention;

FIGS. 47-49 are perspective views of the driving ramp of the expandablefusion device of FIG. 40 in accordance with one embodiment of thepresent invention;

FIG. 50 is a rear perspective view of an alternative embodiment of anexpandable fusion device shown in an expanded position in accordancewith one embodiment of the present invention;

FIG. 51 is a side cross-sectional view of the expandable fusion deviceof FIG. 50 shown in an expanded position in accordance with oneembodiment of the present invention;

FIG. 52 is an exploded view of the expandable fusion device of FIG. 50in accordance with one embodiment of the present invention;

FIG. 53 is a top view of the expandable fusion device of FIG. 50 shownin an unexpanded position in accordance with one embodiment of thepresent invention;

FIG. 54 is a read end view of the expandable fusion device of FIG. 50shown in an expanded position in accordance with one embodiment of thepresent invention;

FIG. 55 is a perspective view of an endplate of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention;

FIG. 56 is a perspective of a central ramp of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention; and

FIG. 57 is a perspective view of a driving ramp of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention.

FIG. 58 is an exploded view of an alternative embodiment of anexpandable fusion device in accordance with one embodiment of thepresent invention.

FIG. 59 is a side view of the expandable fusion device of FIG. 58 shownin partial cross-section in an unexpanded configuration in accordancewith one embodiment of the present invention.

FIG. 60 is a side view of the expandable fusion device of FIG. 58 shownin an unexpanded configuration in accordance with one embodiment of thepresent invention.

FIG. 61 is a perspective view of the expandable fusion device of FIG. 58shown in an unexpanded configuration in accordance with one embodimentof the present invention.

FIG. 62 is a side view of the expandable fusion device of FIG. 58 shownin partial cross-section in a lordotic expanded configuration inaccordance with one embodiment of the present invention.

FIG. 63 is a side view of the expandable fusion device of FIG. 58 shownin a lordotic expanded configuration in accordance with one embodimentof the present invention.

FIG. 64 is a perspective view of the expandable fusion device of FIG. 58shown in a lordotic expanded configuration in accordance with oneembodiment of the present invention.

FIG. 65 is a side view of the expandable fusion device of FIG. 58 shownin partial cross-section in a fully expanded configuration in accordancewith one embodiment of the present invention.

FIG. 66 is a side view of the expandable fusion device of FIG. 58 shownin a fully expanded configuration in accordance with one embodiment ofthe present invention.

FIG. 67 is a perspective view of the expandable fusion device of FIG. 58shown in a fully expanded configuration in accordance with oneembodiment of the present invention.

FIG. 68 is an exploded view of an expandable fusion device having aratcheting mechanism in accordance with some embodiments.

FIGS. 69A-69C are side views of the expandable fusion device of FIG. 68in the process of expansion in accordance with some embodiments.

FIGS. 70A-70C are different views of the expandable fusion device ofFIG. 68 in a contracted state in accordance with some embodiments.

FIGS. 71A-71C are different views of the expandable fusion device ofFIG. 68 in a tipped state without full expansion in accordance with someembodiments.

FIGS. 72A-72C are different views of the expandable fusion device ofFIG. 68 in a fully expanded state in accordance with some embodiments.

FIG. 73 is an upper view of the expandable fusion device of FIG. 68 inaccordance with some embodiments.

FIG. 74 is an upper cross-sectional view of the expandable fusion deviceof FIG. 68 in accordance with some embodiments.

FIG. 75 is a close up view of the ratcheting mechanism of the expandablefusion device of FIG. 68 in accordance with some embodiments.

FIG. 76 is a close up view of the ratchet teeth of the expandable fusiondevice of FIG. 68 in accordance with some embodiments.

FIG. 77 is a top perspective view of the expandable fusion device ofFIG. 68 in accordance with some embodiments.

FIGS. 78A-78G are top perspective views of the expandable fusion deviceof FIG. 68 transitioning from a locked configuration to a disengagedconfiguration in accordance with some embodiments.

FIG. 79 is an exploded view of an expandable fusion device having anexpandable spacing mechanism in accordance with some embodiments.

FIG. 80 is a diagram showing a view of an exemplary “locked”configuration of the fusion device of FIG. 79.

FIG. 81 is a diagram showing a view of an exemplary “disengaged”configuration of the fusion device of FIG. 79.

FIGS. 82A-82C are side views of the expandable fusion device of FIG. 79in the process of expansion in accordance with some embodiments.

FIGS. 83A-83C are different views of the expandable fusion device ofFIG. 79 in a contracted state in accordance with one embodiment of thepresent invention.

FIGS. 84A-84B are different views of the expandable fusion device ofFIG. 79 in a tipped state without full expansion in accordance with oneembodiment.

FIGS. 85A-85C are different views of the expandable fusion device ofFIG. 79 in a fully expanded state according to one embodiment of thepresent invention.

FIG. 86 is a diagram showing an alternative view of the fusion device ofFIG. 79 in the locked position.

FIG. 87 is a diagram showing another alternative view of the fusiondevice of FIG. 79 in the locked position.

FIG. 88 is a diagram showing the stem's position as the fusion device ofFIG. 79 is expanding.

FIG. 89 is a diagram showing the fusion device of FIG. 79 in a lockedposition.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 2 and 3. The fusiondevice 10 engages the endplates 4 and 5 of the adjacent vertebral bodies2 and 3 and, in the installed position, maintains normal intervertebraldisc spacing and restores spinal stability, thereby facilitating anintervertebral fusion. The expandable fusion device 10 can bemanufactured from a number of materials including titanium, stainlesssteel, titanium alloys, non-titanium metallic alloys, polymericmaterials, plastics, plastic composites, PEEK, ceramic, and elasticmaterials. In an embodiment, the expandable fusion device 10 can beconfigured to be placed down an endoscopic tube and into the disc spacebetween the adjacent vertebral bodies 2 and 3.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device.

With reference to FIGS. 2-7, an embodiment of the fusion device 10 isshown. In an exemplary embodiment, the fusion device 10 includes a firstendplate 14, a second endplate 16, a central ramp 18, and a driving ramp260. In an embodiment, the expandable fusion device 10 can be configuredto be placed down an endoscopic tube and into the disc space between theadjacent vertebral bodies 2 and 3. One or more components of the fusiondevice 10 may contain features, such as through bores, that facilitateplacement down an endoscopic tube. In an embodiment, components of thefusion device 10 are placed down the endoscopic tube with assembly ofthe fusion device 10 in the disc space.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. Turning now toFIGS. 2-7 and 10, in an exemplary embodiment, the second endplate 16 hasa first end 39 and a second end 41. In the illustrated embodiment, thesecond endplate 16 further comprise an upper surface 40 connecting thefirst end 39 and the second end 41, and a lower surface 42 connectingthe first end 39 and the second end 41. In an embodiment, the secondendplate 16 further comprises a through opening 44, as seen on FIG. 11.The through opening 44, in an exemplary embodiment, is sized to receivebone graft or similar bone growth inducing material and further allowthe bone graft or similar bone growth inducing material to be packed inthe central opening in the central ramp 18.

As best seen in FIGS. 7 and 10, the lower surface 42 includes at leastone extension 46 extending along at least a portion of the lower surface42, in an embodiment. In an exemplary embodiment, the extension 46 canextend along a substantial portion of the lower surface 42, including,along the center of the lower surface 42. In the illustrated embodiment,the extension 46 includes a generally concave surface 47. The concavesurface 47 can form a through bore with the corresponding concavesurface 47 (not illustrated) of the first endplate 14, for example, whenthe device 10 is in an unexpanded configuration. In another exemplaryembodiment, the extension 46 includes at least one ramped surface 48. Inanother exemplary embodiment, there are two ramped surfaces 48, 50 withthe first ramped surface 48 facing the first end 39 and the secondramped surface facing the second end 41. In an embodiment, the firstramped surface 48 can be proximate the first end 39, and the secondramped surface 50 can be proximate the second end 41. It is contemplatedthat the slope of the ramped surfaces 48, 50 can be equal or can differfrom each other. The effect of varying the slopes of the ramped surfaces48, 50 is discussed below.

In one embodiment, the extension 46 can include features for securingthe endplate 16 when the expandable fusion device 10 is in an expandedposition. In an embodiment, the extension 46 includes one or moreprotuberances 49 extending from the lateral sides 51 of the extension.In the illustrated embodiment, there are two protuberances 49 extendingfrom each of the lateral sides 51 with each of the sides 53 having oneof the protuberances 49 extending from a lower portion of either end. Aswill be discussed in more detail below, the protuberances 49 can befigured to engage the central ramp 18 preventing and/or restrictinglongitudinal movement of the endplate 16 when the device 10 is in anexpanded position.

As illustrated in FIGS. 2-5, in one embodiment, the upper surface 40 ofthe second endplate 16 is flat and generally planar to allow the uppersurface 40 of the endplate 16 to engage with the adjacent vertebral body2. Alternatively, as shown in FIG. 15, the upper surface 40 can becurved convexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral body 2. It is also contemplatedthat the upper surface 40 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 in alordotic fashion. While not illustrated, in an exemplary embodiment, theupper surface 40 includes texturing to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

Referring now to FIGS. 2-8, in an exemplary embodiment, the central ramp18 has a first end 20, a second end 22, a first side portion 24connecting the first end 20 and the second end 22, and a second sideportion 26 (best seen on FIG. 5) on the opposing side of the centralramp 12 connecting the first end 20 and the second end 22. The firstside portion 24 and the second side portion 26 may be curved, in anexemplary embodiment. The central ramp 18 further includes a lower end28, which is sized to receive at least a portion of the first endplate14, and an upper end 30, which is sized to receive at least a portion ofthe second endplate 16.

The first end 20 of the central ramp 18, in an exemplary embodiment,includes an opening 32. The opening 32 can be configured to receive anendoscopic tube in accordance with one or more embodiments. The firstend 20 of the central ramp 18, in an exemplary embodiment, includes atleast one angled surface 33, but can include multiple angled surfaces.The angled surface 33 can serve to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace.

The second end 22 of the central ramp 18, in an exemplary embodiment,includes an opening 36. The opening 36 extends from the second end 22 ofthe central ramp 18 into a central guide 37 in the central ramp 18.

In an embodiment, the central ramp 18 further includes one or moreramped surfaces 33. As best seen in FIG. 8, the one or more rampedsurfaces 33 positioned between the first side portion 24 and the secondside portion 26 and between the central guide 37 and the second end 22.In an embodiment, the one or more ramped surfaces 33 face the second end22 of the central ramp 18. In one embodiment, the central ramp 18includes two ramped surfaces 33 with one of the ramped surfaces 33 beingsloped upwardly and the other of the ramped surfaces 33 being slopeddownwardly. The ramped surfaces 33 of the central ramp can be configuredand dimensioned to engage the ramped surface 48 in each of the first andsecond endplates 14, 16.

Although the following discussion relates to the second side portion 26of the central ramp 18, it should be understood that it also equallyapplies to the first side portion 24 in embodiments of the presentinvention. In the illustrated embodiment, the second side portion 26includes an inner surface 27. In an embodiment, the second side portion26 further includes a lower guide 35, a central guide 37, and an upperguide 38. In the illustrated embodiment, the lower guide 35, centralguide 37, and the upper guide 38 extend out from the inner surface 27from the second end 22 to the one or more ramped surfaces 31. In theillustrated embodiment, the second end 22 of the central ramp 18 furtherincludes one or more guides 38. The guides 38 can serve to guide thetranslational movement of the first and second endplates 14, 16 withrespect to the central ramp 18. For example, protuberances 49 on thesecond endplate 16 may be sized to be received between the central guide37 and the upper guide 38. Protuberances 49 of the first endplate 16 maybe sized to be received between the central guide 37 and the lower guide35. A first slot 29 may be formed proximate the middle of the upperguide 38. A second slot 31 may be formed between end of the upper guide38 and the one or more ramped surfaces 33. The protuberances 49 may besized to be received within the first slot 29 and/or the second slot 31when the device 10 is in the expanded position.

Referring now to FIGS. 4-7 and 9, the driving ramp 260 has a throughbore 262. In an embodiment, the driving ramp 260 is generallywedge-shaped. As illustrated, the driving ramp 260 may comprise a wideend 56, a narrow end 58, a first side portion 60 connecting the wide end56 and the narrow end 58, and a second side portion 62 connecting thewide end 56 and the narrow end 58. The driving ramp 260 further maycomprise ramped surfaces, including an upper ramped surface 64 and anopposing lower ramped surface 66. The upper ramped surface 64 and thelower ramped surface 66 may be configured and dimensioned to engage theramped surface 50 proximate the second end 41 in of the first and thesecond endplates 14, 16. The first and second side portions 60, 62 mayeach include grooves 68 that extend, for example, in a directionparallel to the longitudinal axis of the through bore 262. The grooves68 may be sized to receive the central guide 37 on the interior surface27 of each of the side portions 24, 26 of the central ramp 18. In thismanner, the grooves 68 together with the central guide 37 can surface toguide the translational movement of the driving ramp 260 in the centralramp 18.

A method of installing the expandable fusion device 10 of FIG. 1 is nowdiscussed in accordance with one embodiment of the present invention.Prior to insertion of the fusion device 10, the intervertebral space isprepared. In one method of installation, a discectomy is performed wherethe intervertebral disc, in its entirety, is removed. Alternatively,only a portion of the intervertebral disc can be removed. The endplatesof the adjacent vertebral bodies 2, 3 are then scraped to create anexposed end surface for facilitating bone growth across theintervertebral space. One or more endoscopic tubes can then be insertedinto the disc space. The expandable fusion device 10 can then beintroduced into the intervertebral space down an endoscopic tube andseated in an appropriate position in the intervertebral disc space.

After the fusion device 10 has been inserted into the appropriateposition in the intervertebral disc space, the fusion device 10 can thenbe expanded into the expanded position. To expand the fusion device 10,the driving ramp 260 may move in a first direction with respect to thecentral ramp 18. Translational movement of the driving ramp 260 throughthe central ramp 18 may be guided by the central guide 37 on each of thefirst and second side portions 24, 26 of the central ramp 18. As thedriving ramp 260 moves, the upper ramped surface 64 pushes against theramped surface 50 proximate the second end 41 of the second endplate 16,and the lower ramped surface 66 pushes against the ramped surface 50proximate the second end 41 of the first endplate 14. In addition, theramped surfaces 33 in the central ramp 18 push against the rampedsurface 48 proximate the first end 41 of the first and second endplates14, 16. In this manner, the first and second endplates 14, 16 are pushedoutwardly into an expanded configuration. As discussed above, thecentral ramp 16 includes locking features for securing the endplates 14,16.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the rampedsurfaces 48, 50 and the angled surfaces 62, 64. As best seen in FIG. 16,the endplates 14, 16 can be expanded in any of the following ways:straight rise expansion, straight rise expansion followed by a toggleinto a lordotic expanded configuration, or a phase off straight riseinto a lordotic expanded configuration.

Turning back to FIGS. 2-7, in the event the fusion device 10 needs to berepositioned or revised after being installed and expanded, the fusiondevice 10 can be contracted back to the unexpanded configuration,repositioned, and expanded again once the desired positioning isachieved. To contract the fusion device 10, the central ramp 18 is movedwith respect to the central ramp 260 away from the central ramp 260. Asthe central ramp 18 moves, the ramped surfaces 33 in the central ramp 18ride along the ramped surfaces 48 of the first and second endplates 14,16 with the endplates 14, 16 moving inwardly into the unexpandedposition.

With reference now to FIG. 17, fusion device 10 is shown with anexemplary embodiment of artificial endplates 100. Artificial endplates100 allows the introduction of lordosis even when the endplates 14 and16 of the fusion device 10 are generally planar. In one embodiment, theartificial endplates 100 have an upper surface 102 and a lower surface104. The upper surfaces 102 of the artificial endplates 100 have atleast one spike 106 to engage the adjacent vertebral bodies. The lowersurfaces 104 have complementary texturing or engagement features ontheir surfaces to engage with the texturing or engagement features onthe upper endplate 14 and the lower endplate 16 of the fusion device 10.In an exemplary embodiment, the upper surface 102 of the artificialendplates 100 have a generally convex profile and the lower surfaces 104have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 10 can be used with only oneartificial endplate 100 to introduce lordosis even when the endplates 14and 16 of the fusion device 10 are generally planar. The artificialendplate 100 can either engage endplate 14 or engage endplate 16 andfunction in the same manner as described above with respect to twoartificial endplates 100.

With reference to FIGS. 11-14, an embodiment for placing an expandablefusion device 10 into an intervertebral disc space is illustrated. Theexpandable fusion device 10 can be introduced into the intervertebralspace down an endoscopic tube utilizing a tool 70 that is attached toendplate 16, with the second endplate 16 being first placed down thetube with tool 70 and into the disc space, as seen in FIG. 11. Afterinsertion of the second endplate 16, the first endplate 14 can be placeddown the same endoscopic tube with tool 72 and into the disc space, asshown on FIG. 12. Following the first endplate 14, the central ramp 12can be placed down the same endoscopic tube and into the disc spaceguided by tools 70 and 72, as shown on FIGS. 13 and 14.

Referring now to FIGS. 18-23, an alternative embodiment of theexpandable fusion device 10 is shown. In an exemplary embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, and an actuator assembly 200. As will be discussed inmore detail below, the actuator assembly 200 drives the central ramp 18which forces apart the first and second endplates 14, 16 to place theexpandable fusion device in an expanded position. One or more componentsof the fusion device 10 may contain features, such as through bores,that facilitate placement down an endoscopic tube. In an embodiment,components of the fusion device 10 are placed down the endoscopic tubewith assembly of the fusion device 10 in the disc space.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With additionalreference to FIG. 24, in an exemplary embodiment, the second endplate 16has a first end 39 and a second end 41. In the illustrated embodiment,the second endplate 16 further comprise an upper surface 40 connectingthe first end 39 and the second end 41, and a lower surface 42connecting the first end 39 and the second end 41. While notillustrated, in an embodiment, the second endplate 16 further comprisesa through opening. The through opening, in an exemplary embodiment, issized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the second endplate 16 isflat and generally planar to allow the upper surface 40 of the endplate16 to engage with the adjacent vertebral body 2. Alternatively, as shownin FIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. While notillustrated, in an exemplary embodiment, the upper surface 40 includestexturing to aid in gripping the adjacent vertebral bodies. Although notlimited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In one embodiment, the second endplate 16 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an exemplaryembodiment, the first and second side portions 202, 204 each includeramped surfaces 206, 208. In the illustrated embodiment, the rampedsurfaces 206, 208 extend from the first end 39 of the second endplate 16to bottom surfaces 210, 212 of each of the side portions 202, 204. Inone embodiment, the ramped surfaces 206, 208 are forward facing in thatthe ramped surfaces 206, 208 face the first end 39 of the secondendplate. As previously discussed, the slope of the ramped surfaces 206,208 may be varied as desired for a particular application.

In an embodiment, the first and second side portions 202, 204 eachcomprise at least one protuberance 214. In an exemplary embodiment, thefirst and second side portions 202, 204 each comprise a firstprotuberance 214, a second protuberance 216, and a third protuberance218. In one embodiment, the protuberances 214, 216, 218 extend from theinterior surface 220 of the first and second side portions 202, 204. Inan exemplary embodiment, the protuberances 214, 216, 218 extend at thelower side of the interior surface 220. As best seen in FIG. 24, thefirst and the second protuberances 214, 216 form a first slot 222, andthe second and third protuberances 216, 218 form a second slot 224.

As best seen in FIG. 24, the lower surface 42 of the second endplate 16,in an embodiment, includes a central extension 224 extending along atleast a portion of the lower surface. In the illustrated embodiment, thecentral extension 224 extends between the first and second side portions202 and 204. In an exemplary embodiment, the central extension 224 canextend from the second end 41 of the endplate 16 to the central portionof the endplate. In one embodiment, the central extension 224 includes agenerally concave surface 226 configured and dimensioned to form athrough bore with the corresponding concave surface 226 (notillustrated) of the first endplate 14. The central extension 224 canfurther include, in an exemplary embodiment, a ramped surface 228. Inthe illustrated embodiment, the ramped surface 228 faces the first end39 of the endplate 16. The ramped surface 228 can be at one end of thecentral extension 224. In an embodiment, the other end of the centralextension 224 forms a stop 230. In the illustrated embodiment, the stop230 is recessed from the second end 41 of the second endplate 16.

Referring to FIGS. 25-27, in an exemplary embodiment, the central ramp18 includes a body portion 232 having a first end 234 and a second end236. In an embodiment, the body portion 232 includes at least a firstexpansion portion 238. In an exemplary embodiment, the body portion 232includes a first expansion portion 238 and a second expansion portion240 extending from opposing sides of the body portion with each of thefirst and second expansion portions 238, 240 having a generallytriangular cross-section. In one embodiment, the expansion portions 238,240 each have angled surfaces 242, 244 configured and dimensioned toengage the ramped surfaces 206, 208 of the first and second endplates14, 16 and force apart the first and second endplates 14, 16. In anembodiment, the engagement between the angled surfaces 242, 244 of theexpansion portions 238, 240 with the ramped surfaces 206, 208 of thefirst and second endplates 14, 16 may be described as a dovetailconnection.

The second end 236 of the central ramp 18, in an exemplary embodiment,includes opposing angled surfaces 246. The angled surfaces 246 can beconfigured and dimensioned to engage the ramped surface 228 in thecentral extension 224 in each of the first and second endplates 14, 16.In other words, one of the angled surfaces 246 can be upwardly facingand configured, in one embodiment, to engage the ramped surface 228 inthe central extension 224 in the second endplate 16. In an embodiment,the engagement between the angled surfaces 246 of the second end 236 ofthe central ramp 18 with the ramped surface 228 in the first and secondendplates 14, 16 may be described as a dovetail connection.

The second end 236, in an exemplary embodiment, can further include anextension 252. In the illustrated embodiment, the extension 252 isgenerally cylindrical in shape with a through bore 254 extendinglongitudinally therethrough. In one embodiment, the extension 252 caninclude a beveled end 256. While not illustrated, at least a portion ofthe extension 252 can be threaded.

Referring still to FIGS. 25-27, the central ramp 18 can further includefeatures for securing the first and second endplates 14, 16 when theexpandable fusion device 10 is in an expanded position. In anembodiment, the body portion 232 of the central ramp 18 includes one ormore protuberances 248, 250 extending from opposing sides of the bodyportion 232. As illustrated, the protuberances 248, 250, in oneembodiment, can be spaced along the body portion 232. In an exemplaryembodiment, the protuberances 248, 250 can be configured and dimensionedfor insertion into the corresponding slots 222, 224 in the first andsecond endplates 14, 16 when the device 10 is in an expanded position,as best seen in FIGS. 19 and 21. The protuberances 248, 250 can engagethe endplates 14, 16 preventing and/or restricting movement of theendplates 14, 16 with respect to the central ramp 18 after expansion ofthe device 10.

With reference to FIGS. 20-23, in an exemplary embodiment, the actuatorassembly 200 has a flanged end 253 configured and dimensioned to engagethe stop 232 in the central extension 224 of the first and the secondendplates 14, 16. In an embodiment, the actuator assembly 200 furtherincludes an extension 254 that extends from the flanged end 253. In afurther embodiment, the actuator assembly 200 includes a threaded hole256 that extends through the actuator assembly 200. It should beunderstood that, while the threaded hole 256 in the actuator assembly200 is referred to as threaded, the threaded hole 256 may only bepartially threaded in accordance with one embodiment. In an exemplaryembodiment, the threaded hole 256 is configured and dimensioned tothreadingly receive the extension 252 of the central ramp 18.

With additional reference to FIGS. 28-32, a method of installing theexpandable fusion device 10 of FIGS. 18-27 is now discussed inaccordance with one embodiment of the present invention. Prior toinsertion of the fusion device, the disc space may be prepared asdescribed above and then one or more endoscopic tubes may then insertedinto the disc space. The expandable fusion device 10 can then beinserted into and seated in the appropriate position in theintervertebral disc space, as best seen in FIGS. 28-32. The expandablefusion device 10 can be introduced into the intervertebral space down anendoscopic tube (not illustrated), with the central ramp 18 being firstplaced down the tube and into the disc space, as seen in FIG. 28. Afterinsertion of the central ramp, the first endplate 14 can be placed downan endoscopic tube, as shown on FIG. 29, followed by insertion of thesecond endplate 16, as shown on FIG. 30. After the second endplate 16,the actuator assembly 200 can then be inserted to complete assembly ofthe device 10, as best seen in FIG. 31.

After the fusion device 10 has been inserted into and assembled in theappropriate position in the intervertebral disc space, the fusion device10 can then be expanded into the expanded position. To expand the fusiondevice 10, the actuator assembly 200 can be rotated. As discussed above,the actuator assembly 200 is in threaded engagement with the extension250 of the central ramp 18. Thus, as the actuator assembly 200 isrotated in a first direction, the central ramp 18 moves toward theflanged end 253 of the actuator assembly 200. In another exemplaryembodiment, the actuator assembly 200 can be moved in a linear directionwith the ratchet teeth as means for controlling the movement of thecentral ramp 18. As the central ramp 18 moves, the angled surfaces 242,244 in the expansion portions 238, 240 of the central ramp 18 pushagainst the ramped surfaces 206, 208 in the first and second sideportions 202, 204 of the first and second endplates 14, 16. In addition,the angled surfaces 246 in the second end 236 of the central ramp 18also push against the ramped surfaces 228 in the central extension 224of each of the endplates 14, 16. This is best seen in FIGS. 22-23.

Since the expansion of the fusion device 10 is actuated by a rotationalinput, the expansion of the fusion device 10 is infinite. In otherwords, the endplates 14, 16 can be expanded to an infinite number ofheights dependent on the rotational advancement of the actuator assembly200. As discussed above, the central ramp 16 includes locking featuresfor securing the endplates 14, 16.

In the event the fusion device 10 needs to be repositioned or revisedafter being installed and expanded, the fusion device 10 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 10, the actuator assembly 200 can be rotated in a seconddirection. As discussed above, actuator assembly 200 is in threadedengagement with the extension 250 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a second direction, opposite thefirst direction, the central ramp 18 moves with respect to the actuatorassembly 200 and the first and second endplates 14, 16 away from theflanged end 253. As the central ramp 18 moves, the first and secondendplates are pulled inwardly into the unexpanded position.

Referring now to FIGS. 33-38, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device includes a first endplate 14, a second endplate 16, acentral ramp 18, and an actuator assembly 200. The fusion device 10 ofFIGS. 33-38 and its individual components are similar to the device 10illustrated on FIGS. 18-23 with several modifications. The modificationsto the device 10 will be described in turn below.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With additionalreference to FIG. 39, in an exemplary embodiment, the lower surface 42of the second endplate 16 has been modified. In one embodiment, thecentral extension 224 extending from the lower surface 42 has beenmodified to include a second ramped surface 258 rather than a stop. Inan exemplary embodiment, the second ramped surface 258 faces the secondend 41 of the second endplate 16. In contrast, ramped surface 228 on thecentral extension 228 faces the first end 39 of the second endplate. Theconcave surface 228 connects the ramped surface 228 and the secondramped surface 258.

With reference to FIGS. 35-38, in an exemplary embodiment, the actuatorassembly 200 has been modified to further include a driving ramp 260. Inthe illustrated embodiment, the driving ramp 260 has a through bore 262through which the extension 254 extends. In an embodiment, the drivingramp 260 is generally wedge-shaped. As illustrated, the driving ramp 260may comprise a blunt end 264 in engagement with the flanged end 253. Inan exemplary embodiment, the driving ramp 260 further comprises angledsurfaces 266 configured and dimensioned to engage the second rampedsurface 258 of each of the endplates 14, 16 and force apart the firstand second endplates 14, 16.

Referring now to FIGS. 40-44, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. Aswill be discussed in more detail below, the actuator assembly 200functions, in an embodiment, to pull the central ramp 18 and the drivingramp 300 together, which forces apart the first and second endplates 14,16.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With reference toFIGS. 40-45, in an exemplary embodiment, the first endplate 14 has afirst end 39 and a second end 41. In the illustrated embodiment, thefirst endplate 14 further comprises an upper surface 40 connecting thefirst end 39 and the second end 41, and a lower surface 42 connectingthe first end 39 and the second end 41. While not illustrated, in anembodiment, the first endplate 14 may comprise further comprises athrough opening. The through opening, in an exemplary embodiment, issized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the first endplate 14 is flatand generally planar to allow the upper surface 40 of the endplate 14 toengage with the adjacent vertebral body 2. Alternatively, as shown inFIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. While notillustrated, in an exemplary embodiment, the upper surface 40 includestexturing to aid in gripping the adjacent vertebral bodies. Although notlimited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In one embodiment, the first endplate 14 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an embodiment, thefirst and second side portions each have an interior surface 302 and anexterior surface 304. In an exemplary embodiment, the first and secondside portions 202, 204 each include one or more ramped portions. In theillustrated embodiment, the first and second side portions 202, 204include first ramped portions 306, 308 at the first end 39 of theendplate 14 and second ramped portions 310, 312 at the second end 41 ofthe endplate. The first and second side portions 202, 204 each caninclude a bridge portion 314 connecting the first ramped portions 306,308 and the second ramped portions 310, 312. In an embodiment, the firstramped portions 306, 308 abut the exterior surface 304 of the respectiveside portions 202, 204, and the second ramped portions 310, 312 abut theinterior surface 302 of the respective side portions 202, 204. Asillustrated, the first ramped portions 306, 308 may include tongueportions 316, 318 with the tongue portions 316, 318 extending in anoblique direction with respect to the upper surface 40 of the endplate14. As further illustrated, the second ramped portions 310, 312 mayinclude tongue portions 320, 322 that extend in an oblique directionwith respect to the upper surface 40 of the endplate 14.

As best seen in FIG. 45, the lower surface 42 of the second endplate 16,in an embodiment, includes a central extension 224 extending along atleast a portion of the lower surface. In the illustrated embodiment, thecentral extension 224 extends between the first and second side portions202 and 204. In an exemplary embodiment, the central extension 224 canextend generally between the first ramped portions 306, 308 and thesecond ramped portions 310, 312. In one embodiment, the centralextension 224 includes a generally concave surface 226 configured anddimensioned to form a through bore with the corresponding concavesurface 226 (not illustrated) of the second endplate 16.

With reference to FIGS. 43 and 44, the actuator assembly 200 includes ahead portion 324, a rod receiving extension 326, and a connectingportion 328 that connecting portions that connects the head portion 324and the rod receiving extension 326. As illustrated, the head portion324 may include one or more instrument gripping features 330 that canallow it to be turned by a suitable instrument. In addition, the headportion 324 has a larger diameter than the other components of theactuator assembly 200 to provide a contact surface with the driving ramp300. In the illustrated embodiment, the head portion 324 includes a rim332 that provides a surface for contacting the driving ramp 300. As canbe seen in FIG. 44, in an exemplary embodiment, the rod receivingextension 326 includes an opening sized and dimensioned to receive theextension 336 of the central ramp 18. In an embodiment, the rodreceiving extension 326 includes threading for threadingly engaging theextension 336. In another embodiment, the rod receiving extension 326includes ratchet teeth for engaging the extension 336. In theillustrated embodiment, the head portion 324 and the rod receivingextension 326 are connected by connecting portion 328 which can begenerally cylindrical in shape.

With reference to FIGS. 43, 44, and 46, the central ramp 18 includesexpansion portion 334 and extension 336. As best seen in FIG. 46, theexpansion portion 334 may include an upper portion 338 and side portions340, 342 that extend down from the upper portion 338. In an embodiment,each of the side portions 340, 342 include dual, overlapping rampedportions. For example, side portions 340, 342 each include a firstramped portion 344 that overlaps a second ramped portion 346. In theillustrated embodiment, the first ramped portion 344 faces the extension336 while the second ramped portion 344 faces away from the extension336. In one embodiment, angled grooves 348, 350 are formed in each ofthe first and second ramped portions 344, 346. In another embodiment,the angled grooves 348, 350 are sized to receive the correspondingtongues 316, 318, 320, 322 in the first and second endplates with angledgrooves 348 receiving tongues 320, 322 in the second endplate 16 andangled grooves 350 receiving tongues 316, 318 in the first endplate 14.Although the device 10 is described with tongues 316, 318, 320, 322 onthe endplates 14, 16 and angled grooves 348, 350 on the central ramp 18,it should be understood that that device 10 can also be configured withgrooves on the endplates 14, 16 and tongues on the central ramp 18, inaccordance with one embodiment of the present invention.

In an exemplary embodiment, the extension 336 is sized to be receivedwithin the rod receiving extension 326 of the actuator assembly 200. Inone embodiment, the extension 336 has threading with the extension 336being threadingly received within the rod receiving extension 326. Inanother embodiment, the extension 336 has ratchet teeth with theextension 336 being ratcheted into the rod receiving extension 336. Inan embodiment, the extension 336 include nose 352 at the end of theextension 336.

With reference to FIGS. 47-49, in an exemplary embodiment, the drivingramp 300 includes an upper portion 354 having an upper surface 356 andan oblique surface 358. In an embodiment, the driving ramp 300 furtherincludes side portions 360, 362 that extend from the upper portion 354connecting the upper portion 354 with the lower portion 364 of thedriving ramp 300. As best seen in FIGS. 48-49, the driving ramp 300further includes a bore 366, in an exemplary embodiment, sized toreceive the connection portion 328 of the actuator assembly 200. In oneembodiment, the driving ramp 300 moves along the connection portion 328when the actuator assembly 200 is pushing the driving ramp 300. In anexemplary embodiment, the driving ramp 300 further includes contactsurface 368 that engages the rim 332 of the head portion 324 of theactuator assembly 200. In the illustrated embodiment, the contactsurface 368 has a generally annular shape.

In an exemplary embodiment, the side portions 360, 362 of the drivingramp 300 each include overlapping ramped portions. For example, the sideportions 360, 362 each include first ramped portions 370 that overlapsecond ramped portions 372. In the illustrated embodiment, the firstramped portions 370 face central ramp 18 while the second rampedportions 372 face the opposite direction. In one embodiment, angledgrooves 374, 376 are formed in each of the first and second rampedportions 370, 372. FIG. 48 is a perspective view of the driving ramp 300that shows the top ends of the angled grooves 374 in ramped portions370. FIG. 49 is a perspective view of the driving ramp 300 that showsthe top ends of the angled grooves 376 in ramped portions 372. In anexemplary embodiment, the angled grooves 374, 376 are sized to receivecorresponding tongues 316, 318, 320, 322 in the first and secondendplates 14, 16 with angled grooves 370 receiving tongues 316, 318 inthe second endplate 16 and angled grooves 372 receiving tongues 320, 322in the first endplate 14. Although the device 10 is described withtongues 316, 318, 320, 322 in the first and second endplates 14, 16 andangled grooves 370, 372, 374, 376 on the driving ramp 300, it should beunderstood that that device 10 can also be configured with grooves onthe second endplate 16 and tongues on the driving ramp 300, inaccordance with one embodiment of the present invention.

Turning now to FIGS. 40-42, a method of installing the expandable fusiondevice 10 of FIGS. 40-49 is now discussed in accordance with oneembodiment of the present invention. Prior to insertion of the fusiondevice, the disc space may be prepared as described above. Theexpandable fusion device 10 can then be inserted into and seated in theappropriate position in the intervertebral disc space. The expandablefusion device 10 is then introduced into the intervertebral space, withthe end having the expansion portion 334 of the central ramp 18 beinginserted. In an exemplary method, the fusion device 10 is in theunexpanded position when introduced into the intervertebral space. In anexemplary method, the intervertebral space may be distracted prior toinsertion of the fusion device 10. The distraction provides somebenefits by providing greater access to the surgical site making removalof the intervertebral disc easier and making scraping of the endplatesof the vertebral bodies 2, 3 easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can then beexpanded into the expanded position, as best seen in FIG. 42. To expandthe fusion device 10, an instrument is engaged with the head portion 324of the actuator assembly 200. The instrument is used to rotate actuatorassembly 200. As discussed above, actuator assembly 200 is threadinglyengaged with the extension 336 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a first direction, the central ramp18 is pulled toward the actuator assembly 200. In an exemplaryembodiment, the actuator assembly 200 is moved in a linear directionwith the ratchet teeth engaging as means for controlling the movement ofthe actuator assembly 200 and the central ramp 18. As the central ramp18 is pulled towards the actuator assembly 200, the first rampedportions 344 of the central ramp 18 push against the second rampedportions 310, 312 of the second endplate 16 and the second rampedportions 346 of the central ramp 18 push against first ramped portions306, 308 of the first endplate 14. In this manner, the central ramp 18acts to push the endplates 14, 16 outwardly into the expanded position.This can best be seen in FIGS. 40-42. As the endplates 14, 16 moveoutwardly the tongues 316, 318, 320, 322 in the endplates 14, 16 ride inthe angled grooves 348, 350 with the tongues 320, 322 in the secondendplate 16 riding in angled grooves 348 and the tongues 316, 318 in thefirst endplate 14 riding in angled grooves 350.

As discussed above, the actuator assembly 200 also engages driving ramp300; thus, as the actuator assembly 200 is rotated in a first direction,the actuator assembly 200 pushes the driving ramp 300 towards thecentral ramp 18 in a linear direction. As the driving ramp 300 is pushedtowards the central ramp 18, the first ramped portions 370 of thedriving ramp 300 push against the first ramped portions 306, 308 of thesecond endplate 16 and the second ramped portions 372 of the drivingramp 300 push against the second ramped portions 310, 312 of the firstendplate 14. In this manner, the driving ramp 300 also acts to push theendplates 14, 16 outwardly into the expanded position. This can best beseen in FIGS. 40-42. As the endplates 14, 16 move outwardly the tongues316, 318, 320, 322 in the endplates 14, 16 ride in the angled grooves370, 372 with the tongues 316, 318 in the second endplate 16 riding inangled grooves 370 and the tongues 320, 322 in the first endplate 14riding in angled grooves 372.

Since the expansion of the fusion device 10 is actuated by a rotationalinput, the expansion of the fusion device 10 is infinite. In otherwords, the endplates 14, 16 can be expanded to an infinite number ofheights dependent on the rotational advancement of the actuator assembly200.

Referring now to FIGS. 50-54, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. Aswill be discussed in more detail below, the actuator assembly 200functions, in an embodiment, to pull the central ramp 18 and the drivingramp 300 together, which forces apart the first and second endplates 14,16. In an embodiment, the expandable fusion device may contain features,such as a through bore, that facilitate placement down an endoscopictube. In an embodiment, the assembled fusion device 10 may be placeddown the endoscopic tube and then expanded.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. It should beunderstood that, in an embodiment, the first endplate 14 is configuredto interlock with the second endplate 16. With additional reference toFIG. 55, in an exemplary embodiment, the first endplate 14 has a firstend 39 and a second end 41. As illustrated, the first end 39 may bewider than the second end 41. In the illustrated embodiment, the firstendplate 14 further comprises an upper surface 40 connecting the firstend 39 and the second end 41, and a lower surface 42 connecting thefirst end 39 and the second end 41. As best seen in FIG. 54, the lowersurface 42 can be curved concavely such that the first and secondendplates 14, 16 form a through bore when the device 10 is in a closedposition. In an embodiment, the first endplate 14 may comprise a throughopening 44. The through opening 44, in an exemplary embodiment, is sizedto receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the first endplate 14 is flatand generally planar to allow the upper surface 40 of the endplate 14 toengage with the adjacent vertebral body 2. Alternatively, as shown inFIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. As illustrated, inan exemplary embodiment, the upper surface 40 includes texturing to aidin gripping the adjacent vertebral bodies. For example, the uppersurface 40 may further comprise texturing 400 to engage the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

In one embodiment, the first endplate 14 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an embodiment, thefirst and second side portions 202, 204 each include an interior surface302 and an exterior surface 304. In an embodiment, the first end 39 ofthe first endplate 14 is generally designed and configured to fit overthe second end 41 of the second endplate 16 when the device 10 is in aclosed position. As illustrated, the first and second side portions 202,204 each may include first ramped portions 306, 308, second rampedportions 310, 312, and/or central ramped portion 402.

In an embodiment, the first ramped portions 306, 308 are proximate thefirst end 39 of the endplate 14. In accordance with embodiment of thepresent invention, the first ramped portions 306, 308 of the firstendplate 14 are generally designed and configured to fit over the secondramped portions 310, 312 of the second endplate 16 when the device 10 isin a closed position. In an exemplary embodiment, the first rampedportions 306, 308 generally face the first end 39 and can extend in anoblique direction with respect to the upper surface 40, for example. Asillustrated, the first ramped portions 306, 308 may include tongueportions 316, 318 extending in an oblique direction with respect to theupper surface 40 of the endplate 14.

In an embodiment, the second ramped portions 310, 312 are proximate thesecond end 41 of the endplate 14. In an exemplary embodiment, the secondramped portions 310, 312 can extend in an oblique direction with respectto the upper surface 40 and generally face the second end 41. The firstand second side portions 202, 204, in an embodiment, each can include abridge portion 314 connecting the first ramped portions 306, 308 and thesecond ramped portions 310, 312. As further illustrated, the secondramped portions 310, 312 may include tongue portions 320, 322 thatextend in an oblique direction with respect to the upper surface 40 ofthe endplate 14.

In an embodiment, the endplate 14 further may include a central rampedportion 402 proximate the bridge portion 314. In the illustratedembodiment, the endplate 14 includes a central ramped portion 402proximate the bridge portion 314 of the second side portion 204. In anexemplary embodiment, the central ramped portion 402 can extend in anoblique direction with respect to the upper surface 40 and face thefirst end 39 of the endplate 14. As illustrated, the first rampedportions 306, 308 may include tongue portions 316, 318 with the tongueportions 316, 318 extending in an oblique direction with respect to theupper surface 40 of the endplate 14.

With reference to FIGS. 50-52 and 54, in an embodiment, the actuatorassembly 200 includes a head portion 324, an extension 404, and athrough bore 406 that extends longitudinally through the actuatorassembly 200. As illustrated, the head portion 324 may include one ormore instrument gripping features 330 that can allow it to be turned bya suitable instrument. In addition, the head portion 324 has a largerdiameter than the other components of the actuator assembly 200 toprovide a contact surface with the driving ramp 300. In the illustratedembodiment, the head portion 324 includes a rim 332 that provides asurface for contacting the driving ramp 300. In an embodiment, theextension 404 is a generally rod-like extension. In another embodiment,the extension 404 includes ratchet teeth for engaging the extension 336.

With reference to FIGS. 51, 52, and 56, the central ramp 18 has a firstend 408 and a second end 410. In an embodiment, the central ramp 18includes a first expansion portion 412, a second expansion portion 414,a rod-receiving extension 416, and a through bore 418 that extendslongitudinally through the central ramp 18. In an exemplary embodiment,first expansion portion 412 can be proximate the first end 408 of thecentral ramp 18. As best seen in FIG. 56, the first expansion portion412 may include side portions 420, 422. In an embodiment, each of theside portions 420, 422 includes dual, overlapping ramped portions thatextend in oblique directions with respect to the through bore 418. Forexample, side portions 420, 422 each include a first ramped portion 424that overlaps a second ramped portion 426. In the illustratedembodiment, the first ramped portion 424 faces the rod-receivingextension 416 while the second ramped portion 426 faces the oppositedirection. In one embodiment, angled grooves 428, 430 are formed in eachof the first and second ramped portions 424, 426. In an exemplaryembodiment, the angled grooves 428, 430 are sized to receive thecorresponding tongues 316, 318, 320, 322 in the first and secondendplates 14, 16 with angled grooves 428 receiving tongues 320, 322 inthe second endplate 16 and angled grooves 430 receiving tongues 316, 318in the first endplate 14. Although the device 10 is described withtongues 316, 318, 320, 322 on the endplates 14, 16 and angled grooves428, 430 on the central ramp 18, it should be understood that thatdevice 10 can also be configured with grooves on the endplates 14, 16and tongues on the central ramp 18, in accordance with one embodiment ofthe present invention.

In an embodiment, the second expansion portion 414 is located on therod-receiving extension 416 between the first end 408 and the second end410 of the central ramp 18. In an exemplary embodiment, the secondexpansion portion 414 includes central ramped portions 432. In oneembodiment, the second expansion portion 414 includes two central rampedportions 432 on opposite sides of the rod-receiving extension 416. In anexemplary embodiment, the central ramped portions 424 extend in anoblique direction with respect to the through bore 418 and face thesecond end 410 of the central ramp 18.

The rod-receiving extension 416 extends from the first expansion portion412 and has an opening 434 at the second end of the central ramp 18. Inan embodiment, the rod-receiving extension 416 is sized and configuredto receive the extension 404 of the actuator assembly 200. In anembodiment, the rod-receiving extension 416 has threading with therod-receiving extension 416 threadingly receiving extension 404 of theactuator assembly 200. In another embodiment, the rod-receivingextension 416 has ratchet teeth with the extension 404 being ratchetedinto the rod-receiving extension 416.

With reference to FIGS. 50-52 and 57, in an exemplary embodiment, thedriving ramp 300 includes an upper portion 354 having an upper surface356 and an oblique surface 358. In an embodiment, the driving ramp 300further includes a bore 366, in an exemplary embodiment, sized toreceive the extension 404 of the actuator assembly 200. In theillustrated, embodiment, the upper portion 354 has a hole 436 thatextends through the upper surface 356 to the bore 366. Set screw 438 maybe inserted through the hole 436 to secure the driving ramp 300 to theactuator assembly 200. In one embodiment, the driving ramp 300 furtherincludes contact surface 368 that engages the rim 332 of the headportion 324 of the actuator assembly 200. In the illustrated embodiment,the contact surface 368 has a generally annular shape.

In an embodiment, the driving ramp 300 further includes side portions360, 362 that extend from the upper portion 354 connecting the upperportion 354 with the lower portion 364 of the driving ramp 300. In anexemplary embodiment, the side portions 360, 362 of the driving ramp 300each include a ramped portion 438. In the illustrated embodiment, theramped portion 438 faces central ramp 300. In an embodiment, the rampedportion 438 is configured and dimensioned to engage the ramped portions306, 308 at the first end 39 of the second endplate 16. In oneembodiment, angled grooves 440 are formed in the ramped portions 316,318. In an exemplary embodiment, the angled grooves 440 are sized toreceive the corresponding tongues 316, 318 in the second endplate 16.Although the device 10 is described with tongues 316, 318 on the secondendplate 16 and angled grooves 440 on the driving ramp 300, it should beunderstood that that device 10 can also be configured with grooves onthe second endplate 16 and tongues on the driving ramp 300, inaccordance with one embodiment of the present invention.

A method of installing the expandable fusion device 10 of FIGS. 50-57 isnow discussed in accordance with one embodiment of the presentinvention. Prior to insertion of the fusion device, the disc space maybe prepared as described above. The expandable fusion device 10 can thenbe inserted into and seated in the appropriate position in theintervertebral disc space. In an embodiment, the device 10 is assembledprior to insertion. The expandable fusion device 10 can be introducedinto the intervertebral space, with the end having the first end 408 ofthe central ramp 18 being inserted. In an exemplary method, the fusiondevice 10 is in the unexpanded position when introduced into theintervertebral space. In an exemplary method, the intervertebral spacemay be distracted prior to insertion of the fusion device 10. Thedistraction provides some benefits by providing greater access to thesurgical site making removal of the intervertebral disc easier andmaking scraping of the endplates of the vertebral bodies 2, 3 easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpand into the expanded position. To expand the fusion device 10, aninstrument is engaged with the head portion 324 of the actuator assembly200. The instrument is used to rotate actuator assembly 200. Asdiscussed above, actuator assembly 200 is threadingly engaged with therod receiving extension 416 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a first direction, the central ramp18 is pulled toward the actuator assembly 200. In an exemplaryembodiment, the actuator assembly 200 is moved in a linear directionwith the ratchet teeth engaging as means for controlling the movement ofthe actuator assembly 200 and the central ramp 18.

As the central ramp space 18 is pulled towards the actuator assembly200, the central ramp 18 acts to push endplates 14, 16 outwardly intothe expanded position. By way of example, the first ramped portions 424,second ramped portions 426, and central ramped portions 432 push againstthe corresponding ramped portions in the first and second endplates 14,16. The first ramped portions 424 in the first expansion portion 412 ofthe central ramp 18 push against the second ramped portions 310, 312 ofthe second endplate 16 with the corresponding tongues 320, 322 in thesecond ramped portions 310, 312 of the second endplate 16 riding inangled grooves 428 in the first ramped portions 424 in the firstexpansion portion 412. The second ramped portions 426 in the firstexpansion portion 412 push against the first ramped portions 316, 318 ofthe first endplate 14 with the corresponding tongues 316, 318 in firstramped portions 316, 318 of the first endplate 14 riding in angledgrooves 430 in the second ramped portions 426 in the first expansionportion 412. The central ramped portions 432 in the second expansionportion 414 push against the central ramped portion 402 in the first andsecond endplates 14, 16.

As discussed above, the actuator assembly 200 also engages driving ramp300; thus, as the actuator assembly 200 is rotated in a first direction,the actuator assembly 200 pushes the driving ramp 300 towards thecentral ramp 18 in a linear direction. As the driving ramp 300 is pushedtowards the central ramp 18, the driving ramp 300 also acts to push theendplates 14, 16 outwardly into the expanded position. By way ofexample, the ramped portions 438 of the driving ramp 300 push againstramped portions 306, 308 at the first end 39 of the second endplate 16.As the endplates 14, 16 move outwardly, the tongues 316, 318 in theramped portions 306, 308 of the second endplate 16 ride in the angledgrooves 440 in the ramped portions 438 of the driving ramp 300.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the variousramped portions in the central ramp 18, the driving ramp 300, and thefirst and second endplates 14, 16. As best seen in FIG. 16, theendplates 14, 16 can be expanded in any of the following ways: straightrise expansion, straight rise expansion followed by a toggle into alordotic expanded configuration, or a phase off straight rise into alordotic expanded configuration.

Referring now to FIG. 58, an alternative embodiment of the expandablefusion device 10 is shown in which the expandable fusion device 10expands into a lordotic expanded configuration. In the illustratedembodiment, the expandable fusion device 10 includes a first endplate14, a second endplate 16, an actuator assembly 200, a driving ramp 300,and a body 500. As will be discussed in more detail below, the actuatorassembly 200 functions, in an embodiment, to pull the driving ramp 300and the body 500 together, which forces apart the first and secondendplates 14, 16. For example, the actuator assembly 200 may be rotatedto pull the driving ramp 300 toward the body 500. When this occurs, theexpandable fusion device 10 first expands into a lordotic expandedconfiguration (FIGS. 62-64) and then expands in height until it is fullyexpanded (FIGS. 65-67). In embodiments, expandable fusion device 10 mayhave two stages of expansion, generally referred to as lordotic stageand parallel stage. In lordotic stage, the expandable fusion device 10may expand at one end to achieve a lordotic angle. The expandable fusiondevice 10 may hen expand in parallel sage wherein the lordotic expansionmay be maintained at both ends of the expandable fusion device 10 mayexpand at generally constant rates. In an embodiment, the expandablefusion device 10 may contain features, such as a through bore, thatfacilitate placement down an endoscopic tube. In an embodiment, theassembled fusion device 10 may be placed down the endoscopic tube andthen expanded.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. It should beunderstood that, in an embodiment, the first endplate 14 is configuredto interlock with the second endplate 16. In an exemplary embodiment,the first endplate 14 has a first end 39 and a second end 41. In theillustrated embodiment, the first endplate 14 further comprises a plateportion 502 that may extend between first end 39 and the second end 41.Plate portion 502 may comprise an upper surface 40 and a lower surface42. In an embodiment, the first endplate 14 may comprise a throughopening 44. The through opening 44, in an exemplary embodiment, may besized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the plate portion 502 is flatand generally planar to allow the upper surface 40 of the plate portion502 to engage with the adjacent vertebral body 2. Alternatively, asshown in FIG. 15, the upper surface 40 can be curved convexly orconcavely to allow for a greater or lesser degree of engagement with theadjacent vertebral body 2. It is also contemplated that the uppersurface 40 can be generally planar but includes a generally straightramped surface or a curved ramped surface. The ramped surface allows forengagement with the adjacent vertebral body 2 in a lordotic fashion. Asillustrated, in an exemplary embodiment, the upper surface 40 includestexturing to aid in gripping the adjacent vertebral bodies. For example,the upper surface 40 may further comprise texturing 400 to engage theadjacent vertebral bodies. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

In one embodiment, the first endplate 14 further comprises front sideextensions 504 that extend from plate portion 502. As illustrated, thefront side extensions 504 may extend from either side of plate portion502 proximate to second end 41 of first endplate 14. The front sideextensions 504 may extend opposite from the upper surface 40 of plateportion 502. In one embodiment, the first endplate 14 may furthercomprise rear side extensions 506 that extend from plate portion 502. Asillustrated, the rear side extensions 506 may extend from either side ofplate portion 502 proximate to first end 39 of first endplate 14. Therear side extensions 506 may extend opposite from the upper surface 40of plate portion 502. As illustrated, the front side extensions 504 andthe rear side extensions 506 may each include ramped portions. Forexample, the front side extension 504 may include front ramped portions508 and the rear side extensions 506 may include rear ramped portions510. The front ramped portions 508 and the rear ramped portions 510 maybe considered ramped as they may be at an oblique angle with respect tolongitudinal axis 512 of expandable fusion device 10. In an exemplaryembodiment, the front ramped portions 508 may generally face the secondend 41, and the rear ramped portions 510 may generally face the firstend 39.

Embodiments of actuator assembly 200 will now be described in moredetail with reference to FIG. 58. In the illustrated embodiment, theactuator assembly 200 is in the form of a drive screw. As illustrated,the actuator assembly 200 may include a head portion 324 and anextension 404. As illustrated, the head portion 324 may include one ormore instrument gripping features 330 that can allow it to be turned bya suitable instrument. In addition, the head portion 324 may have alarger diameter than the other components of the actuator assembly 200to provide a contact surface with the body 500. In the illustratedembodiment, ring 514 may ride in groove 516 on head portion 324. In someembodiments, ring 514 may be a compressible ring, such as a c-ring asshown on FIG. 58, that is configured to retain head portion 324 in rearthroughbore 536 of body 500. In an embodiment, the extension 404 is agenerally rod-like extension that may be threaded for engaging acorresponding opening 522 in driving ramp 300. In another embodiment,the extension 404 may include ratchet teeth (not shown) for engagingopening 522 in driving ramp 300.

Embodiments of driving ramp 300 will now be described in more detailwith respect to FIG. 58. As illustrated, the driving ramp 300 mayinclude a ramped body portion 518 and an extension 520. In theillustrated embodiment, extension 520 may extend from ramped bodyportion 518 toward first end 39 of expandable fusion device 10.Extension 520 may include an opening 522 that may engage extension 404of actuator assembly 200. In embodiments, extension 520 may threadinglyengage the extension 404 of actuator assembly 200. Rotation of drivingramp 300 may be limited so that when actuator assembly 200 may berotated, driving ramp 300 may be pulled toward body 500. Driving ramp300 may be secured to actuator assembly 200 at a front end of expandablefusion device 10. In embodiments, the front end of expandable fusiondevice 10 may be the front of the expandable fusion device 10 so thatthe driving ramp 300 may be considered the nose of the expandable fusiondevice 10. In embodiments, the front end 524 of driving ramp 300 may beangled, rounded, or otherwise tapered so that the driving ramp may serveto distract the adjacent vertebral bodies when the expandable fusiondevice 10 is inserted into an intervertebral space.

As illustrated, driving ramp 300 may include front endplate engagingramps 526. Front endplate engaging ramps 526 may be at an oblique anglewith respect to longitudinal axis 512 of the expandable fusion device10. As illustrated, a pair of front endplate engaging ramps 526 thatengage second endplate 16 may be on one side of driving ramp whileanother pair of front endplate engaging ramps 526 that engage firstendplate 14 may be on an opposite side of driving ramp 300. Inoperation, front endplate engaging ramps 526 may engage front rampedportions 508 of the first and second endplates 14, 16. The first andsecond endplates 14, 16 may ride up the front endplate engaging ramps526 as the driving ramp 300 may be pulled towards the body 300 causingthe first and second endplates 14, 16 to be pushed relatively apart suchthat a height of expandable fusion device 10 may be increased.

Embodiments of body 500 will now be described in more detail withrespect to FIG. 58. As illustrated, the body 500 may have a first bodyend 528 and a second body end 530. Lateral sides 532 may connect thefirst body end 528 and the second body end 530. In the illustratedembodiment, the body 500 may have a central opening 534 that may extendthrough the body 500 transverse to longitudinal axis 512 of expandablefusion device. As illustrated, first body end 528, second body end 530,and lateral sides 532 may define central opening 534. Rear throughbore536 may be formed through second body end 530. Rear throughbore 536 maybe centrally positioned and generally aligned with longitudinal axis 512of expandable fusion device 10. As previously described, head portion324 of actuator assembly 200 may be retained in rear throughbore 536,for example, using ring 514. Washer 515 may also be retained oncorresponding grooves of head portion 324. Rear throughbore 506 may alsobe threaded, for example, to facilitate engagement with an insertiondevice. Second body end 530 may also include tool engaging features,such as side recesses 538, which may facilitate use of a device forinsertion of expandable fusion device 10 into a desired position in apatient. First body end 528 may include a corresponding frontthroughbore 540. As illustrated, front throughbore 540 may be centrallypositioned and generally aligned with longitudinal axis 512 ofexpandable fusion device. Extension 404 of actuator assembly 200 mayextend through front throughbore 540 to engage driving ramp 300.

As illustrated, second body end 530 may include rear endplate engagingramps 542. Rear endplate engaging ramps 542 may be at an oblique anglewith respect to longitudinal axis 512 of the expandable fusion device10. In operation, rear endplate engaging ramps 542 may engage rearramped portions 510 of the first and second endplates 14, 16. Asillustrated, a pair of rear endplate engaging ramps 542 that engagesecond endplate 16 may be on one side of second body end 530 whileanother pair of rear endplate engaging ramps 542 (not seen on FIG. 58)that engage first endplate 14 may be on an opposite side of second body530. The first and second endplates 14, 16 may ride up the rear endplateengaging ramps 542 as the driving ramp 300 may be pulled towards thebody 300 causing the first and second endplates 14, 16 to be pushedrelatively apart such that a height of expandable fusion device 10 maybe increased.

As previously described, the expandable fusion device 10 shown on FIG.58 may first expand lordotically and then expand in parallel until fullexpansion of the expandable fusion device 10 may be reached. To achievethis lordotic expansion, the front ramped portions 508 and rear rampedpotions 510 of the first and second endplates 14, 16 may be at adifferent angle with respect to longitudinal axis 512 than the frontendplate engaging ramps 526 of the driving ramp 300 and the rearendplate engaging ramps 542 of the body 500. This difference in anglesmay be present when the expandable fusion device 10 is in the unexpandedconfiguration. As the driving ramp 300 may be pulled back towards thebody 500, the position of the first and second endplates 14, 16 and/orthe driving ramp 300 and the body 500 with respect to body 500 maychange so that the difference in angles may be reduced and potentiallyapproach zero as the first and second endplates 14, 16 are pushedoutward. As this angle is being reduced, the rear portion of theexpandable fusion device may be expanding causing a lordotic angle. Whenthis angle is reduced (or reaches approximately zero), the first andsecond endplates 14, 16 may then expand in parallel with the first end39 and second end 41 expanding at approximately the same height untilthe expandable fusion device 10 may reach its full height. The lordoticangle may be maintained while the first and second endplates 14, 16expand in parallel.

FIGS. 59 to 61 illustrate the expandable fusion device 10 in theunexpanded configuration in accordance with present embodiments. As seenon FIG. 60, the expandable fusion device 10 may have a lordotic angleθ_(LA) of approximately 0° when unexpanded. By way of example, the firstand second endplates 14, 16 may be generally aligned with longitudinalaxis 512 of expandable fusion device 10. In accordance with presentembodiments, lordotic expansion of expandable fusion device 10 may beachieved by use of different in ramp angles with respect to longitudinalaxis 512. As best seen on FIG. 59, rear endplate engaging ramps 542 ofthe body 500 may have an angle α_(body) and rear ramped portions 510 offirst and second endplates 14, 16 may have an angle α_(rearendplate).The front endplate engaging ramps 526 of the driving ramp 300 may havean angle α_(driving) ramp and the front ramped portions 508 of the firstand second endplates 14, 16 may have an angle α_(frontendplate). Theseangles may be selected, for example, to provide a desired rate of heightincrease during expansion of expandable fusion device 10. By way ofexample, the angles may each individually by selected, for example, fromabout 5° to about 85° and alternatively from about 35° to about 65°.However, as described above, embodiments may provide differences inthese angles, for example, to drive the lordotic expansion. As best seenon FIG. 59, the difference between the angles α_(rearendplate) andα_(body) may be provided by Δ_(rear), and the difference between theangles α_(frontendplate) and α_(driving ramped) may be provided byΔ_(front). Δ_(rear) and Δ_(front) may be the same or different. By wayof example, Δ_(rear) and Δ_(front) may each range from 1° to about 20°and, alternatively, from about 2° to about 5°.

FIGS. 62 to 64 illustrate the expandable fusion device 10 in a lordoticexpanded configuration in accordance present embodiments. The expandablefusion device 10 may be expanded to provide a lordotic angle θ_(LA) ofup to about 15° and, more particularly, of about 4° to about 10°.Lordotic angles θ_(LA) of up to 12° may be desired in certainapplications, such as cervical, but other lordotic angles θ_(LA) may bedesired in alternative applications.

To expand the expandable fusion device 10, driving ramp 300 may be movedin a first direction with respect to body 500. By way of example,driving ramp 300 may be pulled towards body 500. In some embodiments,actuator assembly 200 (best seen on FIG. 58) may be rotated to pulldriving ramp 300 towards body 500. As driving ramp 300 may be pulledtowards body 500, the driving ramp 300 and body 500 may engage the firstand second endplates 14, 16. By way of example, the front rampedportions 508 of the first and second endplates 14, 16 may engage thefront endplate engaging ramps 526 of the driving ramp 300 and the rearramped portions 510 of the first and second endplates 14, 16 may engagethe rear endplate engaging ramps 542 of the body 500. However, becauseof the difference in ramp angles (shown as Δ_(rear) and Δ_(front) onFIG. 59), the first and second endplates 14, 16 may not ride up thefront endplate engaging ramps 526 and the rear endplate engaging ramps542 to increase the height of the expandable fusion device. Instead, insome embodiments, the first and second endplates 14, 16 may pivot at thecontact point between the first and second endplates 14, 16 and the body500 causing expansion of the endplates 14, 16 at the opposite end. Asseen in FIGS. 62-64, this pivoting may result in expansion of the firstand second endplates 14, 16 into an expanded lordotic configuration. Aswill be appreciated, pivoting of the first and second endplates 14, 16may cause the angles α_(rearendplate) and α_(frontendplate) with respectto longitudinal axis 512 to change, thus reducing the difference in rampangles Δ_(rear), Δfront. When the difference in ramp angles Δ_(rear),Δ_(front) approaches 0° (e.g., within 0.5°, 0.1°, or less), lordoticexpansion may stop, and expandable fusion device 10 may be in itslordotic expanded configuration.

FIGS. 65 to 67 illustrate expandable fusion device 10 in a fullyexpanded configuration, in accordance with present embodiments. In someembodiments, it may be desired to further expand the expandable fusiondevice 10 from the lordotic expanded configuration of FIGS. 62-64. Byway of example, continued movement of driving ramp 300, for example,translational movement towards body 500, may cause further expansion ofexpandable fusion device 10. This further expansion may be consideredparallel expansion as both ends of the expandable fusion device 10 mayexpand at the same rate. Expansion may be continued, for example, untilthe expandable fusion device 10 has reached its fully expandedconfiguration or until a desired height of expandable fusion device 10has been achieved. Expansion of expandable fusion device 10 may belimited by engagement of driving ramp 300 with body 500.

In the event the fusion device 10 needs to be repositioned or revisedafter being installed and expanded, the fusion device 10 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 10, an instrument can be used to rotate the actuatorassembly 200 in a second direction that is opposite the first direction.Rotation of the actuator assembly 200 in the opposite direction mayresult in movement of the body 500 and the driving ramp 300 away fromone another. As the body 500 and driving ramp 300 move away from oneanother, the endplates 14, 16 move inwardly into the unexpandedposition.

Expanded heights of expandable fusion device 10 may typically range from7 mm to 12 mm, but may be larger or smaller, including as small as 5 mm,and as large as 16 mm, although the size is dependent on the patient,and the joint into which the expandable fusion device 10 may beimplanted. Expandable fusion device 10 may be implanted within any levelof the spine, and may also be implanted in other joints of the body,including joints of the hand, wrist, elbow, shoulder, hip, knee, ankle,or foot.

Although the preceding discussion only discussed having a single fusiondevice 10 in the intervertebral space, it is contemplated that more thanone fusion device 10 can be inserted in the intervertebral space. It isfurther contemplated that each fusion device 10 does not have to befinally installed in the fully expanded state. Rather, depending on thelocation of the fusion device 10 in the intervertebral disc space, theheight of the fusion device 10 may vary from unexpanded to fullyexpanded. It should be noted that, as well as the height being variedfrom an unexpanded state to an expanded state, the fusion 10 may bepositioned permanently anywhere between the expanded state and theunexpanded state.

In some embodiments, an expandable fusion device can be provided wherebyexpansion is performed via a ratcheting mechanism. By providing aratcheting mechanism, this advantageously provides for rapid,convenient, non-continuous expansion of the fusion device.

FIG. 68 is an exploded view of an expandable fusion device having aratcheting mechanism in accordance with some embodiments. The expandablefusion device 600 comprises a first endplate 620, a second endplate 630,a body 610 positioned between the first endplate 620 and the secondendplate 630, a stem 660 and associated collar 670, and a nose 680. Thestem 660 and associated collar 670 advantageously provide anon-continuous ratcheting mechanism to the expandable fusion device,whereby the expandable fusion device can alternatingly incrementallyincrease and then stop, until a desired expansion occurs.

The first endplate 620 comprises a lower endplate having a first end 622and a second end 624. The first end 622 comprises a pair of first endramped portions 626 a, 626 b. Each of these ramped portions 626 a, 626 bis configured to engage corresponding lower nose ramps 682 a, 682 b onthe nose 680 to aid with expansion of the expandable fusion device. Thesecond end 624 comprises a pair of second end ramped portions 628 a, 628b. Each of these ramped portions 628 a, 628 b is configured to engagecorresponding rear lower ramps 616 a, 616 b on the body 610 to aid withexpansion of the expandable fusion device. A first side portion 623having a central ramp 627 a and a second side portion 625 having acentral ramp 627 b are positioned between the first end 622 and thesecond end 624 of the first endplate 620. Each of the central ramps 627a, 627 b is configured to engage corresponding front lower ramps 615 a,615 b (not visible) of the base 610 to aid with expansion of theexpandable fusion device. The ramps of the first endplate 620 are formedalong a perimeter that surrounds a central opening 629.

The second endplate 630 comprises an upper endplate having a first end632 and a second end 634. The first end 632 comprises a pair of firstend ramped portions 636 a, 636 b. Each of these ramped portions 636 a,636 b is configured to engage corresponding upper nose ramps 684 a, 684b on the nose 680 to aid with expansion of the expandable fusion device.The second end 634 comprises a pair of second end ramped portions 638 a,638 b. Each of these ramped portions 638 a, 638 b is configured toengage corresponding rear upper ramps 618 a, 618 b on the body 610 toaid with expansion of the expandable fusion device. A first side portion633 having a central ramp 637 a and a second side portion 635 having acentral ramp 637 b are positioned between the first end 632 and thesecond end 634 of the second endplate 630. Each of the central ramps 637a, 637 b is configured to engage corresponding front upper ramps 617 a,617 b of the base 610 to aid with expansion of the expandable fusiondevice. The ramps of the second endplate 630 are formed along aperimeter that surrounds a central opening 639.

The body 610 comprises a front throughbore 612 and a rear throughbore614. The front throughbore 614 comprises an opening for receiving thecollar 670, and hence the stem 660, therethrough. The rear throughbore614 comprises an opening through which one or more tools (e.g., anexpansion tool and a disengagement tool) can pass through, as shown inFIGS. 78B and 78D. In some embodiments, the rear throughbore 614 isthreaded to allow engagement by an insertion tool. In addition, the body610 comprises one or more tool recesses 611 that can be engaged by aninsertion tool to provide easy delivery of the implant into a surgicalsite. As shown in FIG. 68 and discussed above, the body 610 comprises anumber of angled surfaces or ramps that are configured to engagecorresponding ramps on the first endplate 620 or second endplate 630. Asthe ramps slide against one another, this causes expansion of theexpandable fusion device.

The stem 660 and associated collar 670 form a ratcheting mechanism forcausing expansion of the expandable fusion device. The stem 660comprises a head 662 and a shaft 664. The stem 660 (via its head 662) isreceivable within the nose 680 of the implant, whereby it is capable ofrotation. In some embodiments, rotation of the stem 660 causes theimplant to be changed from a “locked” ratcheting configuration into a“disengaged” non-ratcheting configuration, as will be discussed furtherbelow. The head 662 of the stem 660 comprises one or more grooves orslots 668 for receiving one or more nose pins 690 a, 690 b that extendthrough the nose 680. The shaft 664 of the stem 660 comprises anelongate body having an opening 663 for receiving an expansion tool 710(shown in FIG. 78C) therethrough. The stem 660 further comprises ratchetteeth 665 that extend along a length of the shaft 664. In addition, thestem 660 comprises one or more flat areas 667 that are positionedadjacent to the ratchet teeth 665. In some embodiments, the stem 660comprises a pair of flat areas 667 that are positioned 180 degrees apartfrom one another. In some embodiments, the stem 660 comprises a halfring portion 664 that is advantageously designed to hit against the body610 at full expansion in order to prevent over expansion of the device.

The stem 660 is capable of two configurations. In a first “locked”configuration (shown in FIG. 78D), the ratchet teeth 665 of the stem 660are engaged with corresponding ratchet recesses 675 of the collar 670,thereby creating a ratcheting mechanism that provides for expansion ofthe implant 600. In a second “disengaged” configuration (shown in FIG.78E), the stem 660 is rotated such that the one or more flat areas 667are positioned adjacent the ratchet recesses 675, such that theratcheting mechanism is not operable. In this second disengagedconfiguration, the stem 660 is capable of being pulled back, therebycausing contraction of the implant 600.

The stem 660 is insertable through the collar 670, whereby it is placedin either the “locked” ratcheting configuration or the “disengaged”non-ratcheting configuration. In some embodiments, the collar 670comprises a C-shaped ring having inner ratchet recesses 675 formed alongan inner wall. In some embodiments, the collar 670 is housed within thefront throughbore 616 of the body 610. In some embodiments, the collar670 comprises a compressible C-ring type body that is capable ofcompression within the front throughbore 616. In some embodiments, thecollar 670 is not rotatable, and can be keyed into place to preventrotation. Advantageously, the collar 670 can comprise a tab 679 thatprevents rotation of the collar 670 within the body 610. With the stem660 attached to the collar 670, a ratcheting mechanism is formed wherebyan expansion tool 710 (shown in FIG. 78C) can extend through the collar670 and into the stem 660 via the shaft opening 663. The expansion tool710 is capable of pulling or ratcheting the stem 660 in a directiontowards the second ends of the first endplate 620 and second endplate630. As the stem 660 is operably connected to the nose 680, the nose 680is also drawn, thereby causing ramps of the first endplate 620 andsecond endplate 630 to slide up corresponding ramps of the body 610 andnose 680.

The nose 680 comprises a throughhole 685 through which the head 662 ofthe stem 660 can extend therethrough. A pair of nose pins 682 a, 682 bcan then extend through the nose 680 and into the head 662, therebyretaining the stem 660 in the nose 680. As noted above, the nose 680comprises one or more upper nose ramps 684 a, 684 b, which areconfigured to mate and engage corresponding ramps on the second endplate630. In addition, the nose 680 comprises one or more lower nose ramps682 a, 682 b, which are configured to mate and engage correspondingramps on the first endplate 620.

FIGS. 69A-69C are side views of the expandable fusion device of FIG. 68in the process of expansion in accordance with some embodiments. In someembodiments, the expandable fusion device 600 is advantageously capableof expansion, and in particular, lordotic expansion. In someembodiments, the device 600 can begin in a contracted state, as shown inFIG. 69A. Afterwards, by pulling the nose 680 via a ratchetingmechanism, the device 600 can expand and tip into lordosis, as shown inFIG. 69B. Once the device 600 has achieved maximum lordosis, the device600 can continue to expand in height in a parallel fashion, whereby boththe anterior and posterior aspects expand at the same rate, until theimplant 600 reaches a maximum expansion, as shown in FIG. 69C. In otherwords, once the device 600 reaches a particular lordotic angle (as shownin FIG. 69B), the device 600 will maintain the lordotic angle throughoutthe expansion range until maximum expansion has been achieved, as shownin FIG. 69C. More details on the expansion of the device 600 areprovided with respect to FIGS. 70A-72C.

FIGS. 70A-70C are different views of the expandable fusion device ofFIG. 68 in a contracted state in accordance with some embodiments. Fromthe contracted state, the device 600 is capable of first expanding andtipping into lordosis, and then expanding in a parallel fashion. Theangle tipping is driven by a difference in ramp angle x that is seenbetween the first end ramped portions 636 a, 636 b of the secondendplate 630 and the upper nose ramps 684 a, 684 b of the nose 680.Similarly, the same difference in ramp angle x is also seen between thesecond end ramped portions 638 a, 638 b of the second endplate 630 andthe rear upper ramps 618 a, 618 b of the body 610. In other words, atthe contracted height, the difference in angle x between the differentramps causes a gap 702 between the ramps, with a first end gap 702 aformed closer to the first end of the second endplate 630 and a secondend gap 702 b formed closer to the second end of the second endplate630. The degree of the gap 702 will determine what lordosis the devicewill tip into upon expansion. For example, if the degree of the gap 702is 4 degrees (e.g., x=4), the second endplate 630 will tip into 4degrees of lordosis. As the same mechanism is provided for the firstendplate 620, the first endplate 620 will also tip into 4 degrees oflordosis, thereby providing an overall lordosis of 8 degrees once bothendplates 620, 630 have been tipped. In some embodiments, the endplates620, 630 themselves can have built-in lordosis. For example, if thebuilt in lordosis of both endplates 620, 630 was 7 degrees inclusive,then the overall lordosis following expansion wherein x=4 is 15 degreesof lordosis. While the present embodiment shows an angle x difference of4 degrees, the angle can be less or more, thereby resulting in less ormore lordosis.

FIGS. 71A-71C are different views of the expandable fusion device ofFIG. 68 in a tipped state without full expansion in accordance with someembodiments. To tip the expandable fusion device 600 into lordosis, thenose 680 is initially ratcheted or pulled back towards the body 610,thereby causing the gaps x to close and the corresponding ramps to mate.The amount of lordosis will be pre-determined based on the initial rampgap x. In the present embodiment, the expandable fusion device 600 hasbeen tipped into a lordotic angle of 4 degrees for the second endplate630 and 4 degrees for the first endplate 620, thereby resulting in atotal of 8 degrees of lordosis (as shown in FIG. 71B). One skilled inthe art can appreciate that the total degree of lordosis can be lessthan or greater than 8 degrees, and that 8 degrees in just arepresentative example.

FIGS. 72A-72C are different views of the expandable fusion device ofFIG. 68 in a fully expanded state in accordance with some embodiments.As the nose 680 is pulled back further the corresponding ramps of thedevice 600 are fully mated, the implant then begins to expand in overallheight in a parallel fashion. In other words, the anterior and posterioraspects of the device 600 expand at the same rate. As this happens, thedevice maintains the same lordosis allowing the lordotic angle to beseen throughout the expansion range. For example, the degree of lordosisof the device 600 in the fully expanded state (as shown in FIG. 72B) isthe same as the degree of lordosis of the device 600 after the endplateshave been tipped (as shown in FIG. 71B). However, due to furtherparallel expansion, the height of the device 600 in the fully expandedstate (as shown in FIG. 72B) is greater than the height of the device600 after the endplates have been tipped (as shown in FIG. 71B).

The expandable fusion device 600 can advantageously be expanded via aratcheting mechanism. More details regarding the ratcheting mechanism—inparticular, the stem 660 and the collar 670—will be provided withrespect to FIGS. 73-76.

FIG. 73 is an upper view of the expandable fusion device of FIG. 68 inaccordance with some embodiments. From this view, one can see how collar670 is housed in the body 610, and how the stem 660 is received in thecollar 670. The stem 660 is further received in the nose 680, such thatas the stem is pulled back, the nose 680 can also be pulled back therebycausing ratcheted expansion of the device 600.

FIG. 74 is an upper cross-sectional view of the expandable fusion deviceof FIG. 68 in accordance with some embodiments. In this view, one cansee how the stem 660 having ratchet teeth 665 is engaged with the collar670 to create an expandable ratcheting mechanism. In some embodiments,the stem 660 comprises the “male” ratcheting feature, while the collar670 comprises the “female” ratcheting feature.

FIG. 75 is a close up view of the ratcheting mechanism of the expandablefusion device of FIG. 68 in accordance with some embodiments. This viewshows the male ratchet of the stem 660 and the female ratchet of thecollar 670 in more detail. As the stem 660 is pulled back, the collar670 springs open like a C-ring and allows the ratchet teeth 665 of thestem 660 to advance to the next slot or recess 675 formed in the collar670. The stem 660 advantageously moves in increments through the collar670. These non-continuous increments drive height increases. In someembodiments, the height increases can increase in increments greaterthan 0.2 mm and 0.8 mm. In some embodiments, the height increases are inincrements of approximately 0.5 mm.

FIG. 76 is a close up view of the ratchet teeth of the expandable fusiondevice of FIG. 68 in accordance with some embodiments. Each of theratchet teeth 665 comprises an inclusive angle 668 a and a back angle668 b. In some embodiments, the ratchet teeth 665 comprise an inclusiveangle 668 a of between 30 and 60 degrees, and in particular about 45degrees. In some embodiments, the back angle 668 b comprises between 2and 8 degrees, and in particular about 5 degrees. Under load, theratchet connection is pulled in the direction of disengagement.Advantageously, the purpose of the back angle 668 b is to keep the stem660 more engaged, especially in the back area when the device 600 isunder load by pulling the collar 670 closer to the ratchet teeth 665when pulled in the direction of disengagement.

FIG. 77 is a top perspective view of the expandable fusion device ofFIG. 68 in accordance with some embodiments. In this configuration, thefusion device 600 is capable of ratcheted expansion. In addition toproviding ratcheted expansion, the device is also capable of collapseand contraction. To accommodate contraction, the device 600advantageously provides ratchet teeth 665 on only a portion of the stem660, whereby the ratchet teeth 665 are separated by one or more flatareas 667. In the particular embodiment, the device 600 includes twosets of ratchet teeth 665 each of which is adjacent two sets of flatareas 667. These features allow a device to be converted between a“locked” configuration whereby ratcheting is enabled and a “disengaged”configuration whereby ratcheting is disabled. These features arediscussed below with respect to FIGS. 78A-78G.

FIGS. 78A-78G are top perspective views of the expandable fusion deviceof FIG. 68 transitioning from a locked configuration to a disengagedconfiguration in accordance with some embodiments. FIG. 78A shows anexpandable fusion device in a “locked” configuration whereby the deviceis capable of ratcheted expansion. As shown in FIG. 78A, the ratchetteeth 665 of the stem 660 are aligned and engaged with the ratchetrecesses 675 of the collar 670, thereby enabling ratcheted expansion.

FIG. 78B shows the expandable fusion device with an expansion toolinserted therein. The expansion tool 710 is capable of engaging the stem660 in the “locked” configuration, whereby the stem 660 (and hence thenose 680) is capable of being pulled back. As the stem 660 and nose 680are drawn back, this causes incremental ratcheting expansion of thedevice 600 based on the design of the ratchet teeth.

FIG. 78C shows the expandable fusion device when fully expanded. Asshown in the figure, the stem 660 has been pulled further into the body610, thereby causing greater height expansion of the device. The fusiondevice 600 has a relatively higher height in FIG. 78C than in FIG. 78B.Advantageously, the fusion device 600 can also be contracted by asurgeon if desired.

FIG. 78D shows the expandable fusion device prior to contraction withthe device still in a “locked” ratcheting configuration. To contract thedevice 600, a disengagement tool 720 (separate from the expansion tool710) is provided. The disengagement tool 720 comprises a shaft having adistal nub 730. The disengagement tool 720 is advantageously designed torotate the stem 660, such that the device is changed from a “locked”ratchetable configuration to a “disengaged” unratchetable configuration,as discussed above. To rotate the stem 660, the distal nub 730 of thedisengagement tool 720 mates with a correspondingly shaped recess 669 inthe stem 660. With the disengagement tool 720 engaged with the stem 660,the stem 660 can be rotated (e.g., 90 degrees), thereby converting thedevice into a disengaged configuration, as shown in FIG. 78E.

FIG. 78E shows the expandable fusion device in a “disengaged”non-ratchetable configuration. The stem 660 has been rotated such thatits pair of flat areas 667 align and face the collar 670. As such, theratchet teeth 665 of the stem are no longer engaged with ratchet slotsof the collar 670, thereby allowing the stem 660 to be pushed forward tocontract the device.

FIG. 78F shows the expandable fusion device in a “disengaged”configuration whereby the device has been fully contracted. At thisstage, the device 600 is the same height as it was prior to expansion.The device 600 is fully capable of expansion again. A surgeon simplyneeds to rotate the stem 660 in an opposite direction 90 degrees, suchthat the device is brought back into a “locked” ratchetingconfiguration.

FIG. 78G shows the expandable fusion device whereby the device isbrought back to a “locked” ratcheting configuration. By rotating thedisengagement tool 720 in a reverse direction 90 degrees, this rotatesthe stem 660 whereby the ratchet teeth 665 are once again engaged withratchet slots of the collar 670. The fusion device 600 can once again beexpanded via a ratcheting mechanism if desired. Advantageously, theexpandable fusion devices described above are each capable of beinginserted through a minimal incision, as the devices can maintain aminimal profile prior to expansion.

In posterior interbody fusion procedures, surgeons are required toconsider a number of anatomical aspects when implanting a device. Forexample, surgeons must often consider the surrounding nerve roots andavoid disrupting them, or they may need to consider the size of theintervertebral disc being replaced. In many cases, a collapsed discspace is involved that requires surgical intervention to restore height.When the posterior margin of any disc is smaller than the anteriormargin and when the disc is collapsed, the posterior margin is evensmaller, making it very difficult to insert a device. The reducedposterior margin restricts the surgeon because they need the device tobe small enough to be able to be fully implanted while at the same timebeing large enough to fill the anterior space and restore disc height.The expandable fusion device described in more detail below with respectto FIGS. 79-89 provides the advantage of allowing the surgeon the insertthe device at a collapsed height past the posterior margin while notdisrupting the surrounding nerve roots. The device can subsequently beexpanded in the anterior space to restore the disc height and provide anendplate to endplate fit.

FIG. 79 is an exploded view of an expandable fusion device having anexpandable spacing mechanism in accordance with some embodiments. Theexpandable fusion device 722 comprises a first endplate 724, a secondendplate 726, a body 728 positioned between the first endplate 724 andthe second endplate 726, a stem 730, a middle (mid) ramp piece 732, andtwo ramp pins 734. The stem 730 and associated mid ramp piece 732advantageously provide an expandable spacing mechanism to the expandablefusion device. The expandable fusion device can be expanded orcontracted to achieve a desired expansion.

Although the following discussion relates to the first endplate 724, itshould be understood that it also equally applies to the second endplate726, as the second endplate 726 is substantially identical to the firstendplate 724 in various embodiments of the present invention. It shouldbe understood that, in one embodiment, the first endplate 724 isconfigured and dimensioned to interlock with the second endplate 726.The first endplate 724 comprises a lower endplate having a first end 736and a second end 738. The first end 736 comprises a pair of first endramped portions 740 a, 740 b. Each of these ramped portions 740 a, 740 bis configured and dimensioned to engage corresponding lower ramps 742 a,742 b of the front end 744 of the body 728 to aid with expansion of theexpandable fusion device.

The second end 738 of the first endplate 724 comprises a pair of secondend ramped portions 746 a, 746 b. Each of these ramped portions 746 a,746 b is configured and dimensioned to engage corresponding lower ramps748 a, 748 b on the back end 750 of body 728 to aid with expansion ofthe expandable fusion device. The first endplate 724 also includes athird pair of mid ramps 752 a, 752 b that are positioned between thefirst end ramped portions 740 a, 740 b and second end ramped portions746 a, 746 b. It may be desirable for the mid ramps 752 a, 752 b to beconfigured and dimensioned to be positioned near the first end rampedportions 746 a, 746 b, as shown in FIG. 79. Each of the mid ramps 752 a,752 b is configured and dimensioned to engage corresponding lower ramps754 a, 754 b (754 b not visible) of the mid ramp piece 732 to aid withexpansion of the expandable fusion device 722. The mid ramp piece 732may also include upper ramps 755 a, 755 b (755 b not visible) that areconfigured and dimensioned to engage with corresponding mid ramps of thesecond endplate 726. The ramps of the first endplate 724 are formedalong a perimeter that surrounds a central opening 756.

In one embodiment, the body 728 comprises a front throughbore 758 andrear throughbore 760. The front throughbore 758 comprises an opening forreceiving the stem 730 therethrough. The front throughbore 758 mayinclude recesses, as described in more detail below. The rearthroughbore 760 comprises an opening through which one or more tools(e.g., an expansion tool and a disengagement tool) can pass through, asdiscussed with respect to FIGS. 78B and 78D above. In some embodiments,the rear throughbore 760 is threaded to allow engagement by an insertiontool. As shown in FIG. 79 and discussed above, the body 728 comprises atleast one angled surface or ramps that are configured and dimensioned toengage corresponding ramps on the first endplate 724, second endplate726, or mid ramp piece 732. Sliding the ramps against one another causesthe expansion of the expandable fusion device.

The mid ramp piece 732 may include at least one angled surface or rampthat is configured and dimensioned to engage corresponding ramps on thefirst endplate 724, second endplate 726, and/or the body 728, asdiscussed above. The mid ramp piece 732 also includes a throughbore 762that comprises an opening for receiving the stem 730 therethrough. Insome embodiments the throughbore 762 may be threaded to allow it to befixed to the mid ramp piece 732. It is desirable for the stem 730 to beoperable to rotate within the throughbore 762. The mid ramp piece 732may also include at least two openings 732 (one not visible) that areconfigured and dimensioned to receive a portion of each of the two ramppins 734. When the ramp pins 734 are inserted into the openings 732, aportion of them extends outside the openings 764 of the mid ramp piece732. When the mid ramp piece 732 is inserted into the body 728, theportion of the ramp pins 734 that extends outside of the openings 764engages with slots 766 in the body 728. The slots 766 may be configuredand dimensioned on one or more interior surfaces of the body 728. Whenengaged, the ramp pins 734 and slots 766 allow the mid ramp piece 732 toslide horizontally, or translate, within the body 728. In oneembodiment, the slots 766 may be configured and dimensioned in the body728 so that they keep the mid ramp piece 732 on a centerline of theinterior of the body 728, as shown in FIG. 79. In an alternateembodiment, the ramp pins 734 may comprise protrusions that areconfigured and dimensioned as part of the mid ramp piece 732 to engagewith the slots 766.

According to one embodiment, the stem 730 and the mid ramp piece 732form a mechanism for causing expansion of the expandable fusion device.The stem 730 comprises an elongate shaft that may include two portions.In one embodiment, the two portions of the shaft may have differentdiameters, although in other embodiments the shaft may have the samediameter throughout. In one embodiment, the first portion 768 of theshaft may be configured and dimensioned to be received in thethroughbore 762 of the mid ramp piece 732. In embodiments where thethroughbore 762 is threaded, the first portion 768 has correspondingthreads that allow it to matingly engage with the mid ramp piece 732. Asdiscussed above, it may be desirable for the first portion 768 to beoperable to rotate a predetermined amount within the throughbore 762.

A second portion 770 of the stem 730 includes grooves, e.g., teeth 772configured and dimensioned along a portion of the length of the shaft,as shown in FIG. 79. One advantage of including grooves 772 is that, insome embodiments, rotation of the stem 730 causes the expandable fusiondevice to be changed from a “locked” configuration into a “disengaged”configuration, as will be discussed further below. At least part of thestem 730 comprises an elongate body that includes an opening 774 forreceiving a tool, such as an expansion tool or the like, therethrough.In addition, the second portion 770 of the stem 730 comprises one ormore flat areas 776 that are positioned adjacent to the teeth 772. Insome embodiments, the second portion 770 comprises a pair of flat areas776 that are positioned about 180 degrees apart from one another.

According to one embodiment, the stem 730 is capable of twoconfigurations. In a first “locked” configuration shown in FIG. 80, theteeth 772 of the stem 730 are engaged with corresponding recesses 778 ofthe front throughbore 758 of the body 728, as circled in FIG. 80. In asecond “disengaged” configuration, shown in FIG. 81, the stem 730 isrotated such that the one or more flat areas 776 are positioned adjacentthe recesses 778 of the front throughbore 758, such that movement of thestem 730 within the throughbore 758 is possible. In this seconddisengaged configuration, the stem 730 may move back and forth withinthe throughbore 758, causing expansion or contraction of the expandablefusion device, as described in more detail below.

FIGS. 82A-82C are side views of the expandable fusion device 722 of FIG.79 in the process of expansion in accordance with some embodiments. Inone embodiment, the expandable fusion device 722 is advantageouslyoperable to expand and, in particular, lordotically expand. According toone embodiment, the device 722 may begin in a contracted state, as shownin FIG. 82A. When the stem 730 is rotated to the released position, themid ramp piece 732 may be pushed towards the front end of the firstendplate 724 and second endplate 726, as shown in FIG. 82B. When theexpandable fusion device 722 expands, the endplates 724, 726 first tipinto lordosis, as shown in FIG. 82B. Once the fusion device 722 hasachieved maximum lordosis, the device 722 can continue to expand inheight in a parallel fashion, whereby both the anterior and posterioraspects expand at the same rate until the fusion device 722 reaches amaximum expansion, as shown in FIG. 82C. In other words, once the device722 reaches a particular lordotic angle (as shown in FIG. 82B), thedevice 722 will maintain the lordotic angle throughout the expansionrange until maximum expansion has been achieved, as shown in FIG. 82C.More details on the expansion of the device 722 are provided below.

FIGS. 83A-83C are different views of the expandable fusion device ofFIG. 79 in a contracted state in accordance with one embodiment of thepresent invention. From the contracted state, the device 722 is operableto first expand and tip into lordosis, and then expand in a parallelfashion. In one embodiment, the angle tipping is generated by adifference in ramp angle x that is seen between the first end ramps 740a, 740 b and the lower ramps 742 a, 742 b as well as between the midramps 752 a, 752 b and the lower ramps 754 a, 754 b of the mid ramppiece 732. Similarly, the same difference in ramp angle x is seenbetween the corresponding ramped portions of the second endplate 726 andthe body 728 and the mid ramp of the second endplate 726 and the midramp piece 732. In other words, at the contracted height, the differencein angle x between the different ramps causes a first gap 780 betweenthe body 728 and the first and second endplates 724, 726, and a secondgap 782 between the mid ramp piece 732 and the mid ramps 752 a, 752 b ofthe first and second endplates 724, 726.

The degree of the gaps 780, 782 determines what lordosis the device willtip into upon expansion. For example, if the degree of the gaps 780, 782is 4 degrees (e.g., x=4), the first endplate 724 will tip into 4 degreesof lordosis. As the same mechanism is provided for the second endplate726, the second endplate 726 will also tip into 4 degrees of lordosis,thereby providing an overall lordosis of 8 degrees once both endplates724, 726 have been tipped if the endplates 724, 726 do not have anybuilt-in lordosis, as shown in FIG. 83B. In some embodiments, theendplates 724, 726 themselves can have built-in lordosis. For example,if the built-in lordosis of both endplates 724, 726 was 7 degreesinclusive, then the overall lordosis following expansion wherein x=4 is15 degrees of lordosis. While the present embodiment shows an angle xdifference of 4 degrees, the angle can be less or more, therebyresulting in less or more lordosis.

FIGS. 84A-84B are different views of the expandable fusion device ofFIG. 79 in a tipped state without full expansion in accordance with oneembodiment. To tip the expandable fusion device 722 into lordosis, themid ramp piece 732 may be pushed forwards towards the front end 744 ofthe body 728. In this manner, the first gap 780 and second gap 782 willclose, thereby causing the gaps x to close to zero degrees and thecorresponding ramps to mate, as shown in FIG. 84A. The amount oflordosis will be predetermined based on the first gap 780 and the secondgap 782. For example, if the ramp angle difference is 4 degrees for eachendplate 724, 726 in one embodiment, the total lordosis is 8 degreesonce the endplates are tipped, as shown in FIG. 84B. One skilled in theart can appreciate that the total degree of lordosis can be less than orgreater than 8 degrees, and that 8 degrees in just a representativeexample.

Another way to describe the lordotic and parallel expansion of theexpandable fusion device of FIG. 79 is with respect to the movement ofthe mid ramp piece 732. In other words, the mid ramp piece 732, andtherefore the stem 730, may begin in a fully contracted state, with nolordosis or parallel expansion (assuming zero lordosis of the endplates724, 726). When the mid ramp piece 732 is pushed towards the front end744 of the body 728 by a first predetermined amount from the fullycontracted state, it will engage the ramps and cause the first gap 780and second gap 782 to close, as shown in FIG. 84A. As the mid ramp piece732, and therefore the stem 730 continue to move towards the front end744 of the body 728 by a second predetermined amount, each endplate 724,726 will continue to expand away from one another in parallel, asdescribed further with respect to FIGS. 85A-85C, until fully expanded.

In one embodiment, for instance, the first predetermined amount may be 3mm while the second predetermined amount may be an additional 3 mm, fora total of 6 mm. In this example, the first predetermined amount mayalso be represented as a range between 0.5 mm and 3 mm, for instance,and the second predetermined amount may be represented as a rangebetween 3.5 mm and 6 mm, assuming that the increments of the teeth are0.5 mm increments, as described below. In other words, lordotic movementof each endplate 724, 726, will occur as the mid ramp piece 732, andtherefore the stem 730, is moved up to 3 mm and the first gap 780 andsecond wpage 782 are closed. After 3 mm, the first gap 780 and secondgap 782 are closed, resulting in parallel movement of each endplate 724,726. Similarly, if the mid ramp piece 732, and therefore the stem 730 isthen moved away from the front throughbore 758 near the front end 744 ofthe body 728, the endplates 724, 726 will move towards one another inparallel between 6 mm and 3 mm. When the mid ramp piece 732, andtherefore the stem 730 is moved away from the front throughbore 758 nearthe front end 744 of the body 728 between 3 mm and 0 mm (the fullycontracted state), the endplates 724, 726 will reduce their lordosisuntil there is zero lordosis, as shown in FIG. 83B.

FIGS. 85A-85C are different views of the expandable fusion device ofFIG. 79 in a fully expanded state according to one embodiment of thepresent invention. As the mid ramp piece 732 is pushed further towardsthe front end 744 of the body 728 and the corresponding ramps are fullymated, the fusion device 722 will begin to expand in overall height in aparallel fashion. In other words, the anterior and posterior aspects ofthe device 722 may expand at the same rate. As this happens, the devicemaintains the same lordosis, allowing the lordotic angle to bemaintained throughout the expansion range. For example, the degree oflordosis of the device 722 in the fully expanded state, as shown in FIG.85B, is the same as the degree of lordosis of the device 722 after theendplates have been tipped, shown in FIG. 84B. However, due to furtherparallel expansion, the height of the device 722 in the fully expandedstate (as shown in FIG. 85B) is greater than the height of the device722 after the endplates have been tipped (as shown in FIG. 84B).

FIGS. 86-87 show alternative views of the fusion device 722 in thelocked position. In one embodiment, the expandable fusion device 722comprises a disengaged and a locked position, as described above withrespect to FIG. 80. According to this embodiment, the fusion device 722is operable to expand or collapse in the disengaged position and is notcapable of movement when in the locked position. The device 722 maystart in the locked position when the stem 730 engages with the body728, as shown in the top down view in FIG. 86 and the cross-sectionalview through the middle of the device 722 in FIG. 87. The lockedconnection is circled in FIG. 87 for illustrative purposes.

When the user is ready to expand the fusion device 722, the stem 730 isturned, for example, clockwise by 90 degrees, putting the device 722 inthe disengaged position with no teeth 772 engaged, as shown in FIG. 81.Once in the released position, the user may drive the device 722 up(expanded) and down (contracted) as desired. FIG. 88 shows the stem's730 position as the device is expanding (as compared with the stem's 730position in FIG. 81). The stem 730 advantageously moves continuouslythrough the front throughbore 758, in one embodiment, when in thedisengaged position. The teeth 772 of the stem 730 (circled in FIG. 80)may be configured and dimensioned to drive the overall heightrequirements of the fusion device 722. For instance, the teeth 722 maybe configured and dimensioned with 0.5 mm height increments. In thisembodiment, the tooth 722 profile may be substantially similar to aM3.5×0.45 thread profile, except that the cuts are not helical likethreads but spherical like grooves. The 0.45 mm “pitch” may comprise theincrement that drives the overall height expansion discussed above.These non-continuous increments drive height increases. In someembodiments, the height increases can increase in increments betweenabout 0.2 mm and about 0.8 mm. In other embodiments, the heightincreases are in increments of approximately 0.5 mm.

When the user is satisfied with the magnitude of expansion of the fusiondevice 722, the stem 730 may be turned, for example, counterclockwise by90 degrees such that the teeth 772 of the stem 730 engage with therecesses 778 in the front throughbore 758 of the body 728, locking theimplant as shown in FIG. 89. Any expansion tool known to those skilledin the art may be used to engage with the stem 730, such as the tooldescribed with respect to FIGS. 78B and 78C. Advantageously, theexpandable fusion devices described above are each capable of beinginserted through a minimal incision, as the devices can maintain aminimal profile prior to expansion.

The disclosure being thus described, it will be obvious that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims. Althoughvarious embodiments are described separately herein for the purposes offacilitating their descriptions, those skilled in the art willunderstand that various aspects of each embodiment may be combined withother embodiments as desired.

The invention claimed is:
 1. An implantable system, comprising: anexpandable device, comprising: a first endplate including a first rampedsurface having a first angle and a second ramped surface having a secondangle; a second endplate operatively connected to the first endplate; abody positioned between the first endplate and the second endplate, thebody including a third ramped surface having a third angle; a middleramped piece including a fourth ramped surface having a fourth angle,wherein the first endplate and the second endplate are operable to movelordotically when there is a difference between the first angle and thethird angle and wherein the first endplate and the second endplate areoperable to move in parallel when there is no difference between thefirst angle and the third angle, at least two ramp pins configured to bepositioned within at least two openings of the middle ramped piece andextending into at least two slots of the body, wherein the at least tworamp pins slide along the at least two slots of the body to allow themiddle ramped piece to translate within the body.
 2. The implantablesystem of claim 1, wherein the first endplate and the second endplateare operable to move lordotically when there is a difference between thesecond angle and the fourth angle.
 3. The implantable system of claim 1,wherein the first endplate and the second endplate are operable to movein parallel when there is no difference between the second angle and thefourth angle.
 4. The implantable system of claim 1, wherein a degree oflordosis of the first endplate and the second endplate does not increasewhen there is no difference between the first angle and the third angle.5. The implantable system of claim 1, wherein a degree of lordosis ofthe first endplate and the second endplate does not increase when thereis no difference between the second angle and the fourth angle.
 6. Theimplantable system of claim 1, wherein the middle ramped piece comprisesa stem, and wherein at least a portion of the stem includes teeth. 7.The implantable system of claim 6, wherein the body comprises an openingthat is configured and dimensioned to be engagable with the teeth. 8.The implantable system of claim 7, wherein the first endplate and secondendplate do not move with respect to one another when the teeth areengaged with the opening.
 9. The implantable system of claim 7, whereinthe first endplate and the second endplate are operable to movelordotically when the teeth are disengaged from the opening.
 10. Theimplantable system of claim 7, wherein the first endplate and the secondendplate are operable to move in parallel when the teeth are disengagedfrom the opening.